21697910 has 48 divisors (see below), whose sum is σ = 43559856. Its totient is φ = 7772544.

The previous prime is 21697909. The next prime is 21697913. The reversal of 21697910 is 1979612.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697913) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 62357 + ... + 62703.

It is an arithmetic number, because the mean of its divisors is an integer number (907497).

Almost surely, 2^21697910 is an apocalyptic number.

21697910 is an abundant number, since it is smaller than the sum of its proper divisors (21861946).

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

21697910 is a wasteful number, since it uses less digits than its factorization.

21697910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 417 (or 404 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 35.

The square root of 21697910 is about 4658.1015446209. The cubic root of 21697910 is about 278.9154902208.

The spelling of 21697910 in words is "twenty-one million, six hundred ninety-seven thousand, nine hundred ten".