644577651 has 12 divisors (see below), whose sum is σ = 939297528. Its totient is φ = 425914944.

The previous prime is 644577649. The next prime is 644577653. The reversal of 644577651 is 156775446.

It is an interprime number because it is at equal distance from previous prime (644577649) and next prime (644577653).

It is not a de Polignac number, because 644577651 - 2¹ = 644577649 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644577597 and 644577606.

It is not an unprimeable number, because it can be changed into a prime (644577653) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 315885 + ... + 317918.

It is an arithmetic number, because the mean of its divisors is an integer number (78274794).

Almost surely, 2^644577651 is an apocalyptic number.

644577651 is a deficient number, since it is larger than the sum of its proper divisors (294719877).

644577651 is a wasteful number, since it uses less digits than its factorization.

644577651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 633922 (or 633919 counting only the distinct ones).

The product of its digits is 705600, while the sum is 45.

The square root of 644577651 is about 25388.5338489642. The cubic root of 644577651 is about 863.8236321783.

The spelling of 644577651 in words is "six hundred forty-four million, five hundred seventy-seven thousand, six hundred fifty-one".