21637690 has 32 divisors (see below), whose sum is σ = 40513536. Its totient is φ = 8311680.

The previous prime is 21637673. The next prime is 21637697. The reversal of 21637690 is 9673612.

It is a super-2 number, since 2×21637690² = 936379257072200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21637697) 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 15 ways as a sum of consecutive naturals, for example, 68974 + ... + 69286.

It is an arithmetic number, because the mean of its divisors is an integer number (1266048).

Almost surely, 2^21637690 is an apocalyptic number.

21637690 is a deficient number, since it is larger than the sum of its proper divisors (18875846).

21637690 is a wasteful number, since it uses less digits than its factorization.

21637690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574.

The product of its (nonzero) digits is 13608, while the sum is 34.

The square root of 21637690 is about 4651.6330465762. The cubic root of 21637690 is about 278.6572187477.

The spelling of 21637690 in words is "twenty-one million, six hundred thirty-seven thousand, six hundred ninety".