645785400 has 96 divisors (see below), whose sum is σ = 2155955760. Its totient is φ = 158960640.

The previous prime is 645785389. The next prime is 645785411. The reversal of 645785400 is 4587546.

It is an interprime number because it is at equal distance from previous prime (645785389) and next prime (645785411).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33597 + ... + 49196.

Almost surely, 2^645785400 is an apocalyptic number.

645785400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645785400 is an abundant number, since it is smaller than the sum of its proper divisors (1510170360).

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

645785400 is a wasteful number, since it uses less digits than its factorization.

645785400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82825 (or 82816 counting only the distinct ones).

The product of its (nonzero) digits is 134400, while the sum is 39.

The square root of 645785400 is about 25412.3080415770. The cubic root of 645785400 is about 864.3628127319.

The spelling of 645785400 in words is "six hundred forty-five million, seven hundred eighty-five thousand, four hundred".