21699888 has 160 divisors (see below), whose sum is σ = 70709760. Its totient is φ = 5591040.

The previous prime is 21699883. The next prime is 21699901. The reversal of 21699888 is 88899612.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a self number, because there is not a number n which added to its sum of digits gives 21699888.

It is not an unprimeable number, because it can be changed into a prime (21699883) 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 31 ways as a sum of consecutive naturals, for example, 165583 + ... + 165713.

It is an arithmetic number, because the mean of its divisors is an integer number (441936).

Almost surely, 2^21699888 is an apocalyptic number.

21699888 is a gapful number since it is divisible by the number (28) 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 21699888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35354880).

21699888 is an abundant number, since it is smaller than the sum of its proper divisors (49009872).

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

21699888 is a wasteful number, since it uses less digits than its factorization.

21699888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195 (or 189 counting only the distinct ones).

The product of its digits is 497664, while the sum is 51.

The square root of 21699888 is about 4658.3138580392. The cubic root of 21699888 is about 278.9239653547.

The spelling of 21699888 in words is "twenty-one million, six hundred ninety-nine thousand, eight hundred eighty-eight".