20998857 has 32 divisors (see below), whose sum is σ = 32555520. Its totient is φ = 11905920.

The previous prime is 20998853. The next prime is 20998877. The reversal of 20998857 is 75889902.

It is a happy number.

It is not a de Polignac number, because 20998857 - 2² = 20998853 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20998853) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 66933 + ... + 67245.

It is an arithmetic number, because the mean of its divisors is an integer number (1017360).

Almost surely, 2^20998857 is an apocalyptic number.

It is an amenable number.

20998857 is a deficient number, since it is larger than the sum of its proper divisors (11556663).

20998857 is a wasteful number, since it uses less digits than its factorization.

20998857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 453.

The product of its (nonzero) digits is 362880, while the sum is 48.

The square root of 20998857 is about 4582.4509817346. The cubic root of 20998857 is about 275.8874120706.

The spelling of 20998857 in words is "twenty million, nine hundred ninety-eight thousand, eight hundred fifty-seven".