645251408 has 40 divisors (see below), whose sum is σ = 1271168640. Its totient is φ = 317233280.

The previous prime is 645251353. The next prime is 645251423. The reversal of 645251408 is 804152546.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 768653 + ... + 769491.

It is an arithmetic number, because the mean of its divisors is an integer number (31779216).

Almost surely, 2^645251408 is an apocalyptic number.

It is an amenable number.

645251408 is a deficient number, since it is larger than the sum of its proper divisors (625917232).

645251408 is a wasteful number, since it uses less digits than its factorization.

645251408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1595 (or 1589 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 35.

The square root of 645251408 is about 25401.7993063484. The cubic root of 645251408 is about 864.1245033772.

The spelling of 645251408 in words is "six hundred forty-five million, two hundred fifty-one thousand, four hundred eight".