644766534 has 16 divisors (see below), whose sum is σ = 1432814640. Its totient is φ = 214922160.

The previous prime is 644766503. The next prime is 644766547. The reversal of 644766534 is 435667446.

It is a happy number.

644766534 is a `hidden beast` number, since 6 + 44 + 76 + 6 + 534 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 644766534.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5970007 + ... + 5970114.

It is an arithmetic number, because the mean of its divisors is an integer number (89550915).

Almost surely, 2^644766534 is an apocalyptic number.

644766534 is an abundant number, since it is smaller than the sum of its proper divisors (788048106).

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

644766534 is a wasteful number, since it uses less digits than its factorization.

644766534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11940132 (or 11940126 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 45.

The square root of 644766534 is about 25392.2534250113. The cubic root of 644766534 is about 863.9080004279.

The spelling of 644766534 in words is "six hundred forty-four million, seven hundred sixty-six thousand, five hundred thirty-four".