644706747 has 12 divisors (see below), whose sum is σ = 947027640. Its totient is φ = 422519328.

The previous prime is 644706707. The next prime is 644706749. The reversal of 644706747 is 747607446.

It is not a de Polignac number, because 644706747 - 2⁷ = 644706619 is a prime.

It is not an unprimeable number, because it can be changed into a prime (644706749) 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, 606538 + ... + 607599.

It is an arithmetic number, because the mean of its divisors is an integer number (78918970).

Almost surely, 2^644706747 is an apocalyptic number.

644706747 is a deficient number, since it is larger than the sum of its proper divisors (302320893).

644706747 is a wasteful number, since it uses less digits than its factorization.

644706747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214202 (or 1214199 counting only the distinct ones).

The product of its (nonzero) digits is 790272, while the sum is 45.

The square root of 644706747 is about 25391.0761292230. The cubic root of 644706747 is about 863.8812971891.

It can be divided in two parts, 64470 and 6747, that added together give a palindrome (71217).

The spelling of 644706747 in words is "six hundred forty-four million, seven hundred six thousand, seven hundred forty-seven".