645649139444 has 12 divisors (see below), whose sum is σ = 1129900213764. Its totient is φ = 322820506944.

The previous prime is 645649139393. The next prime is 645649139459. The reversal of 645649139444 is 444931946546.

It can be written as a sum of positive squares in 2 ways, for example, as 28497491344 + 617151648100 = 168812^2 + 785590^2 .

It is a super-2 number, since 2×645649139444² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 642929 + ... + 1305624.

It is an arithmetic number, because the mean of its divisors is an integer number (94158351147).

Almost surely, 2^645649139444 is an apocalyptic number.

It is an amenable number.

645649139444 is a deficient number, since it is larger than the sum of its proper divisors (484251074320).

645649139444 is a wasteful number, since it uses less digits than its factorization.

645649139444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2031394 (or 2031392 counting only the distinct ones).

The product of its digits is 44789760, while the sum is 59.

The spelling of 645649139444 in words is "six hundred forty-five billion, six hundred forty-nine million, one hundred thirty-nine thousand, four hundred forty-four".