644606136942 has 64 divisors (see below), whose sum is σ = 1337806525440. Its totient is φ = 206913014784.

The previous prime is 644606136931. The next prime is 644606136971. The reversal of 644606136942 is 249631606446.

It is a super-2 number, since 2×644606136942² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 60583659 + ... + 60594297.

It is an arithmetic number, because the mean of its divisors is an integer number (20903226960).

Almost surely, 2^644606136942 is an apocalyptic number.

644606136942 is an abundant number, since it is smaller than the sum of its proper divisors (693200388498).

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

644606136942 is a wasteful number, since it uses less digits than its factorization.

644606136942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13977.

The product of its (nonzero) digits is 4478976, while the sum is 51.

The spelling of 644606136942 in words is "six hundred forty-four billion, six hundred six million, one hundred thirty-six thousand, nine hundred forty-two".