645640407 has 12 divisors (see below), whose sum is σ = 955338384. Its totient is φ = 419928480.

The previous prime is 645640403. The next prime is 645640453. The reversal of 645640407 is 704046546.

645640407 is a `hidden beast` number, since 6 + 4 + 5 + 640 + 4 + 0 + 7 = 666.

It is not a de Polignac number, because 645640407 - 2² = 645640403 is a prime.

It is a super-2 number, since 2×645640407² = 833703070302251298, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645640403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 874483 + ... + 875220.

It is an arithmetic number, because the mean of its divisors is an integer number (79611532).

Almost surely, 2^645640407 is an apocalyptic number.

645640407 is a deficient number, since it is larger than the sum of its proper divisors (309697977).

645640407 is a wasteful number, since it uses less digits than its factorization.

645640407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1749750 (or 1749747 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 36.

The square root of 645640407 is about 25409.4550708983. The cubic root of 645640407 is about 864.2981184139.

The spelling of 645640407 in words is "six hundred forty-five million, six hundred forty thousand, four hundred seven".