21320690 has 32 divisors (see below), whose sum is σ = 39631680. Its totient is φ = 8253504.

The previous prime is 21320683. The next prime is 21320743. The reversal of 21320690 is 9602312.

It is a super-2 number, since 2×21320690² = 909143644152200, which contains 22 as substring.

It is a Curzon 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 15 ways as a sum of consecutive naturals, for example, 76832 + ... + 77108.

It is an arithmetic number, because the mean of its divisors is an integer number (1238490).

Almost surely, 2^21320690 is an apocalyptic number.

21320690 is a deficient number, since it is larger than the sum of its proper divisors (18310990).

21320690 is a wasteful number, since it uses less digits than its factorization.

21320690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21320690 is about 4617.4332696857. The cubic root of 21320690 is about 277.2897089271.

The spelling of 21320690 in words is "twenty-one million, three hundred twenty thousand, six hundred ninety".