21690402 has 16 divisors (see below), whose sum is σ = 45932832. Its totient is φ = 6804800.

The previous prime is 21690397. The next prime is 21690407. The reversal of 21690402 is 20409612.

It is an interprime number because it is at equal distance from previous prime (21690397) and next prime (21690407).

It is not an unprimeable number, because it can be changed into a prime (21690407) 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 7 ways as a sum of consecutive naturals, for example, 106224 + ... + 106427.

It is an arithmetic number, because the mean of its divisors is an integer number (2870802).

Almost surely, 2^21690402 is an apocalyptic number.

21690402 is an abundant number, since it is smaller than the sum of its proper divisors (24242430).

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

21690402 is a wasteful number, since it uses less digits than its factorization.

21690402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212673.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21690402 is about 4657.2955671720. The cubic root of 21690402 is about 278.8833160147.

The spelling of 21690402 in words is "twenty-one million, six hundred ninety thousand, four hundred two".