645968408 has 16 divisors (see below), whose sum is σ = 1224801000. Its totient is φ = 319354816.

The previous prime is 645968387. The next prime is 645968429. The reversal of 645968408 is 804869546.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (645968387) and next prime (645968429).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 452918 + ... + 454341.

Almost surely, 2^645968408 is an apocalyptic number.

It is an amenable number.

645968408 is a deficient number, since it is larger than the sum of its proper divisors (578832592).

645968408 is a wasteful number, since it uses less digits than its factorization.

645968408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907354 (or 907350 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 50.

The square root of 645968408 is about 25415.9085613716. The cubic root of 645968408 is about 864.4444551110. Note that the first 4 decimals are identical.

The spelling of 645968408 in words is "six hundred forty-five million, nine hundred sixty-eight thousand, four hundred eight".