645757520 has 40 divisors (see below), whose sum is σ = 1502674656. Its totient is φ = 258081408.

The previous prime is 645757493. The next prime is 645757523. The reversal of 645757520 is 25757546.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645757523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 115919 + ... + 121361.

Almost surely, 2^645757520 is an apocalyptic number.

It is an amenable number.

645757520 is an abundant number, since it is smaller than the sum of its proper divisors (856917136).

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

645757520 is a wasteful number, since it uses less digits than its factorization.

645757520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6939 (or 6933 counting only the distinct ones).

The product of its (nonzero) digits is 294000, while the sum is 41.

The square root of 645757520 is about 25411.7594825703. The cubic root of 645757520 is about 864.3503737276.

The spelling of 645757520 in words is "six hundred forty-five million, seven hundred fifty-seven thousand, five hundred twenty".