21620859 has 16 divisors (see below), whose sum is σ = 31399200. Its totient is φ = 13153536.

The previous prime is 21620843. The next prime is 21620869. The reversal of 21620859 is 95802612.

It is not a de Polignac number, because 21620859 - 2⁴ = 21620843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21620869) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 357 + ... + 6585.

It is an arithmetic number, because the mean of its divisors is an integer number (1962450).

Almost surely, 2^21620859 is an apocalyptic number.

21620859 is a deficient number, since it is larger than the sum of its proper divisors (9778341).

21620859 is a wasteful number, since it uses less digits than its factorization.

21620859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6334.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21620859 is about 4649.8235450391. The cubic root of 21620859 is about 278.5849483060.

The spelling of 21620859 in words is "twenty-one million, six hundred twenty thousand, eight hundred fifty-nine".