645926641920 has 1152 divisors, whose sum is σ = 2828451225600. Its totient is φ = 136317468672.

The previous prime is 645926641907. The next prime is 645926641961. The reversal of 645926641920 is 29146629546.

645926641920 is a `hidden beast` number, since 6 + 4 + 592 + 6 + 6 + 41 + 9 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

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

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 161358639 + ... + 161362641.

It is an arithmetic number, because the mean of its divisors is an integer number (2455252800).

Almost surely, 2^645926641920 is an apocalyptic number.

645926641920 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 645926641920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1414225612800).

645926641920 is an abundant number, since it is smaller than the sum of its proper divisors (2182524583680).

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

645926641920 is a wasteful number, since it uses less digits than its factorization.

645926641920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4092 (or 4072 counting only the distinct ones).

The product of its (nonzero) digits is 5598720, while the sum is 54.

The spelling of 645926641920 in words is "six hundred forty-five billion, nine hundred twenty-six million, six hundred forty-one thousand, nine hundred twenty".