645439298400 has 864 divisors, whose sum is σ = 2563123949568. Its totient is φ = 157547980800.

The previous prime is 645439298369. The next prime is 645439298407. The reversal of 645439298400 is 4892934546.

645439298400 is a `hidden beast` number, since 6 + 4 + 543 + 9 + 2 + 98 + 4 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645439298407) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 320953395 + ... + 320955405.

Almost surely, 2^645439298400 is an apocalyptic number.

645439298400 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 645439298400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1281561974784).

645439298400 is an abundant number, since it is smaller than the sum of its proper divisors (1917684651168).

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

645439298400 is a wasteful number, since it uses less digits than its factorization.

645439298400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2186 (or 2161 counting only the distinct ones).

The product of its (nonzero) digits is 7464960, while the sum is 54.

The spelling of 645439298400 in words is "six hundred forty-five billion, four hundred thirty-nine million, two hundred ninety-eight thousand, four hundred".