645075440 has 40 divisors (see below), whose sum is σ = 1511273808. Its totient is φ = 256056320.

The previous prime is 645075439. The next prime is 645075443. The reversal of 645075440 is 44570546.

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

It is a super-2 number, since 2×645075440² = 832244646582387200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 645075440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645075443) 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, 20297 + ... + 41256.

Almost surely, 2^645075440 is an apocalyptic number.

It is an amenable number.

645075440 is an abundant number, since it is smaller than the sum of its proper divisors (866198368).

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

645075440 is a wasteful number, since it uses less digits than its factorization.

645075440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61697 (or 61691 counting only the distinct ones).

The product of its (nonzero) digits is 67200, while the sum is 35.

The square root of 645075440 is about 25398.3353785243. The cubic root of 645075440 is about 864.0459437731.

The spelling of 645075440 in words is "six hundred forty-five million, seventy-five thousand, four hundred forty".