645137363520 has 1344 divisors, whose sum is σ = 2617288826880. Its totient is φ = 144473849856.

The previous prime is 645137363513. The next prime is 645137363567. The reversal of 645137363520 is 25363731546.

It is a happy number.

645137363520 is a `hidden beast` number, since 6 + 4 + 5 + 1 + 3 + 7 + 3 + 635 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 3342680544 + ... + 3342680736.

It is an arithmetic number, because the mean of its divisors is an integer number (1947387520).

Almost surely, 2^645137363520 is an apocalyptic number.

645137363520 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 645137363520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1308644413440).

645137363520 is an abundant number, since it is smaller than the sum of its proper divisors (1972151463360).

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

645137363520 is a wasteful number, since it uses less digits than its factorization.

645137363520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 412 (or 399 counting only the distinct ones).

The product of its (nonzero) digits is 1360800, while the sum is 45.

The spelling of 645137363520 in words is "six hundred forty-five billion, one hundred thirty-seven million, three hundred sixty-three thousand, five hundred twenty".