21690528 has 24 divisors (see below), whose sum is σ = 56937888. Its totient is φ = 7230144.

The previous prime is 21690527. The next prime is 21690553. The reversal of 21690528 is 82509612.

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (21690523) 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 3 ways as a sum of consecutive naturals, for example, 112876 + ... + 113067.

It is an arithmetic number, because the mean of its divisors is an integer number (2372412).

Almost surely, 2^21690528 is an apocalyptic number.

It is an amenable number.

21690528 is an abundant number, since it is smaller than the sum of its proper divisors (35247360).

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

21690528 is a wasteful number, since it uses less digits than its factorization.

21690528 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225956 (or 225948 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21690528 is about 4657.3090943162. The cubic root of 21690528 is about 278.8838560267.

The spelling of 21690528 in words is "twenty-one million, six hundred ninety thousand, five hundred twenty-eight".