20851980 has 24 divisors (see below), whose sum is σ = 58385712. Its totient is φ = 5560512.

The previous prime is 20851969. The next prime is 20851991. The reversal of 20851980 is 8915802.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20851969) and next prime (20851991).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173707 + ... + 173826.

It is an arithmetic number, because the mean of its divisors is an integer number (2432738).

Almost surely, 2^20851980 is an apocalyptic number.

20851980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20851980 is an abundant number, since it is smaller than the sum of its proper divisors (37533732).

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

20851980 is a wasteful number, since it uses less digits than its factorization.

20851980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347545 (or 347543 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 33.

The square root of 20851980 is about 4566.3968290108. The cubic root of 20851980 is about 275.2426728435.

The spelling of 20851980 in words is "twenty million, eight hundred fifty-one thousand, nine hundred eighty".