644179791 has 16 divisors (see below), whose sum is σ = 915323904. Its totient is φ = 402039264.

The previous prime is 644179777. The next prime is 644179799. The reversal of 644179791 is 197971446.

It is not a de Polignac number, because 644179791 - 2¹⁴ = 644163407 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 644179791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644179799) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 96076 + ... + 102561.

It is an arithmetic number, because the mean of its divisors is an integer number (57207744).

Almost surely, 2^644179791 is an apocalyptic number.

644179791 is a deficient number, since it is larger than the sum of its proper divisors (271144113).

644179791 is a wasteful number, since it uses less digits than its factorization.

644179791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198710.

The product of its digits is 381024, while the sum is 48.

The square root of 644179791 is about 25380.6972126457. The cubic root of 644179791 is about 863.6458663677.

The spelling of 644179791 in words is "six hundred forty-four million, one hundred seventy-nine thousand, seven hundred ninety-one".