645374400 has 336 divisors, whose sum is σ = 2449128960. Its totient is φ = 147046400.

The previous prime is 645374377. The next prime is 645374419. The reversal of 645374400 is 4473546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 897241 + ... + 897959.

Almost surely, 2^645374400 is an apocalyptic number.

645374400 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 645374400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1224564480).

645374400 is an abundant number, since it is smaller than the sum of its proper divisors (1803754560).

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

645374400 is a wasteful number, since it uses less digits than its factorization.

645374400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 772 (or 757 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 33.

The square root of 645374400 is about 25404.2201218616. The cubic root of 645374400 is about 864.1794037605.

The spelling of 645374400 in words is "six hundred forty-five million, three hundred seventy-four thousand, four hundred".