642956820 has 48 divisors (see below), whose sum is σ = 1963942848. Its totient is φ = 155868160.

The previous prime is 642956801. The next prime is 642956863. The reversal of 642956820 is 28659246.

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, 486429 + ... + 487748.

It is an arithmetic number, because the mean of its divisors is an integer number (40915476).

Almost surely, 2^642956820 is an apocalyptic number.

642956820 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

642956820 is an abundant number, since it is smaller than the sum of its proper divisors (1320986028).

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

642956820 is a wasteful number, since it uses less digits than its factorization.

642956820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 974200 (or 974198 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The square root of 642956820 is about 25356.5932254315. The cubic root of 642956820 is about 863.0989781778.

The spelling of 642956820 in words is "six hundred forty-two million, nine hundred fifty-six thousand, eight hundred twenty".