645637520 has 160 divisors (see below), whose sum is σ = 1697034240. Its totient is φ = 226437120.

The previous prime is 645637493. The next prime is 645637547. The reversal of 645637520 is 25736546.

645637520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (645637493) and next prime (645637547).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5083697 + ... + 5083823.

It is an arithmetic number, because the mean of its divisors is an integer number (10606464).

Almost surely, 2^645637520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645637520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (848517120).

645637520 is an abundant number, since it is smaller than the sum of its proper divisors (1051396720).

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

645637520 is a wasteful number, since it uses less digits than its factorization.

645637520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313 (or 307 counting only the distinct ones).

The product of its (nonzero) digits is 151200, while the sum is 38.

The square root of 645637520 is about 25409.3982612733. The cubic root of 645637520 is about 864.2968301672.

The spelling of 645637520 in words is "six hundred forty-five million, six hundred thirty-seven thousand, five hundred twenty".