645751020 has 48 divisors (see below), whose sum is σ = 1817222400. Its totient is φ = 171331776.

The previous prime is 645751003. The next prime is 645751021. The reversal of 645751020 is 20157546.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is not an unprimeable number, because it can be changed into a prime (645751021) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15102 + ... + 38981.

It is an arithmetic number, because the mean of its divisors is an integer number (37858800).

Almost surely, 2^645751020 is an apocalyptic number.

645751020 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645751020 is an abundant number, since it is smaller than the sum of its proper divisors (1171471380).

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

645751020 is a wasteful number, since it uses less digits than its factorization.

645751020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54294 (or 54292 counting only the distinct ones).

The product of its (nonzero) digits is 8400, while the sum is 30.

The square root of 645751020 is about 25411.6315887036. The cubic root of 645751020 is about 864.3474736214.

The spelling of 645751020 in words is "six hundred forty-five million, seven hundred fifty-one thousand, twenty".