645398400 has 384 divisors, whose sum is σ = 2306995200. Its totient is φ = 158146560.

The previous prime is 645398389. The next prime is 645398431. The reversal of 645398400 is 4893546.

It is a tau number, because it is divible by the number of its divisors (384).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8169561 + ... + 8169639.

It is an arithmetic number, because the mean of its divisors is an integer number (6007800).

Almost surely, 2^645398400 is an apocalyptic number.

645398400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645398400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1153497600).

645398400 is an abundant number, since it is smaller than the sum of its proper divisors (1661596800).

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

645398400 is a wasteful number, since it uses less digits than its factorization.

645398400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The square root of 645398400 is about 25404.6924799337. The cubic root of 645398400 is about 864.1901159139.

The spelling of 645398400 in words is "six hundred forty-five million, three hundred ninety-eight thousand, four hundred".