251664220 has 12 divisors (see below), whose sum is σ = 528494904. Its totient is φ = 100665680.

The previous prime is 251664211. The next prime is 251664227. The reversal of 251664220 is 22466152.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (251664227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6291586 + ... + 6291625.

It is an arithmetic number, because the mean of its divisors is an integer number (44041242).

Almost surely, 2^251664220 is an apocalyptic number.

251664220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

251664220 is an abundant number, since it is smaller than the sum of its proper divisors (276830684).

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

251664220 is a wasteful number, since it uses less digits than its factorization.

251664220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12583220 (or 12583218 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 251664220 is about 15863.9282650925. The cubic root of 251664220 is about 631.3552917852.

The spelling of 251664220 in words is "two hundred fifty-one million, six hundred sixty-four thousand, two hundred twenty".