644136631446 has 32 divisors (see below), whose sum is σ = 1606158874368. Its totient is φ = 167308215840.

The previous prime is 644136631433. The next prime is 644136631447.

644136631446 is nontrivially palindromic in base 10.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 644136631395 and 644136631404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644136631447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 697117105 + ... + 697118028.

It is an arithmetic number, because the mean of its divisors is an integer number (50192464824).

Almost surely, 2^644136631446 is an apocalyptic number.

644136631446 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

644136631446 is an abundant number, since it is smaller than the sum of its proper divisors (962022242922).

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

644136631446 is a wasteful number, since it uses less digits than its factorization.

644136631446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1394235156.

The product of its digits is 2985984, while the sum is 48.

The spelling of 644136631446 in words is "six hundred forty-four billion, one hundred thirty-six million, six hundred thirty-one thousand, four hundred forty-six".