21699612 has 72 divisors (see below), whose sum is σ = 61497072. Its totient is φ = 6393600.

The previous prime is 21699607. The next prime is 21699617.

21699612 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (21699607) and next prime (21699617).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21699617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 13912 + ... + 15392.

It is an arithmetic number, because the mean of its divisors is an integer number (854126).

Almost surely, 2^21699612 is an apocalyptic number.

21699612 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21699612, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30748536).

21699612 is an abundant number, since it is smaller than the sum of its proper divisors (39797460).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21699612 is a wasteful number, since it uses less digits than its factorization.

21699612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1539 (or 1534 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 21699612 is about 4658.2842334920. The cubic root of 21699612 is about 278.9227828088.

It can be divided in two parts, 2169 and 9612, that added together give a triangular number (11781 = T₁₅₃).

The spelling of 21699612 in words is "twenty-one million, six hundred ninety-nine thousand, six hundred twelve".