20851870 has 32 divisors (see below), whose sum is σ = 41821920. Its totient is φ = 7432320.

The previous prime is 20851867. The next prime is 20851891. The reversal of 20851870 is 7815802.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1005 + ... + 6535.

It is an arithmetic number, because the mean of its divisors is an integer number (1306935).

Almost surely, 2^20851870 is an apocalyptic number.

20851870 is an abundant number, since it is smaller than the sum of its proper divisors (20970050).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20851870 is a wasteful number, since it uses less digits than its factorization.

20851870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5580.

The product of its (nonzero) digits is 4480, while the sum is 31.

The square root of 20851870 is about 4566.3847844876. The cubic root of 20851870 is about 275.2421888487.

The spelling of 20851870 in words is "twenty million, eight hundred fifty-one thousand, eight hundred seventy".