21611772 has 120 divisors (see below), whose sum is σ = 69630176. Its totient is φ = 5692032.

The previous prime is 21611767. The next prime is 21611783. The reversal of 21611772 is 27711612.

It is a Harshad number since it is a multiple of its sum of digits (27).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 29118 + ... + 29850.

Almost surely, 2^21611772 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21611772, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34815088).

21611772 is an abundant number, since it is smaller than the sum of its proper divisors (48018404).

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

21611772 is a wasteful number, since it uses less digits than its factorization.

21611772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 769 (or 758 counting only the distinct ones).

The product of its digits is 1176, while the sum is 27.

The square root of 21611772 is about 4648.8463084942. The cubic root of 21611772 is about 278.5459141467.

The spelling of 21611772 in words is "twenty-one million, six hundred eleven thousand, seven hundred seventy-two".