644433691158 has 12 divisors (see below), whose sum is σ = 1396272997548. Its totient is φ = 214811230380.

The previous prime is 644433691141. The next prime is 644433691183. The reversal of 644433691158 is 851196334446.

It is a happy number.

644433691158 is a `hidden beast` number, since 64 + 443 + 3 + 6 + 91 + 1 + 58 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17900935848 + ... + 17900935883.

It is an arithmetic number, because the mean of its divisors is an integer number (116356083129).

Almost surely, 2^644433691158 is an apocalyptic number.

644433691158 is an abundant number, since it is smaller than the sum of its proper divisors (751839306390).

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

644433691158 is a wasteful number, since it uses less digits than its factorization.

644433691158 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35801871739 (or 35801871736 counting only the distinct ones).

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

The spelling of 644433691158 in words is "six hundred forty-four billion, four hundred thirty-three million, six hundred ninety-one thousand, one hundred fifty-eight".