20912985 has 20 divisors (see below), whose sum is σ = 37489188. Its totient is φ = 11153376.

The previous prime is 20912923. The next prime is 20912989. The reversal of 20912985 is 58921902.

It can be written as a sum of positive squares in 2 ways, for example, as 7096896 + 13816089 = 2664^2 + 3717^2 .

It is not a de Polignac number, because 20912985 - 2⁸ = 20912729 is a prime.

It is a super-2 number, since 2×20912985² = 874705883220450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20912989) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 25414 + ... + 26223.

Almost surely, 2^20912985 is an apocalyptic number.

It is an amenable number.

20912985 is a deficient number, since it is larger than the sum of its proper divisors (16576203).

20912985 is an equidigital number, since it uses as much as digits as its factorization.

20912985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51654 (or 51645 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 20912985 is about 4573.0717247819. The cubic root of 20912985 is about 275.5108301271.

The spelling of 20912985 in words is "twenty million, nine hundred twelve thousand, nine hundred eighty-five".