645506400 has 432 divisors, whose sum is σ = 2671704000. Its totient is φ = 133862400.

The previous prime is 645506387. The next prime is 645506401. The reversal of 645506400 is 4605546.

645506400 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645506401) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1293351 + ... + 1293849.

It is an arithmetic number, because the mean of its divisors is an integer number (6184500).

Almost surely, 2^645506400 is an apocalyptic number.

645506400 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 645506400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1335852000).

645506400 is an abundant number, since it is smaller than the sum of its proper divisors (2026197600).

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

645506400 is a wasteful number, since it uses less digits than its factorization.

645506400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547 (or 527 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 30.

The square root of 645506400 is about 25406.8179825810. The cubic root of 645506400 is about 864.2383173178.

The spelling of 645506400 in words is "six hundred forty-five million, five hundred six thousand, four hundred".