644663151 has 16 divisors (see below), whose sum is σ = 1041880320. Its totient is φ = 390704760.

The previous prime is 644663119. The next prime is 644663161. The reversal of 644663151 is 151366446.

It is a happy number.

644663151 is a `hidden beast` number, since 6 + 446 + 63 + 151 = 666.

It is not a de Polignac number, because 644663151 - 2⁵ = 644663119 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644663101) 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, 1084995 + ... + 1085588.

It is an arithmetic number, because the mean of its divisors is an integer number (65117520).

Almost surely, 2^644663151 is an apocalyptic number.

644663151 is a deficient number, since it is larger than the sum of its proper divisors (397217169).

644663151 is a wasteful number, since it uses less digits than its factorization.

644663151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2170603 (or 2170597 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 644663151 is about 25390.2176241166. The cubic root of 644663151 is about 863.8618244505.

The spelling of 644663151 in words is "six hundred forty-four million, six hundred sixty-three thousand, one hundred fifty-one".