644654491 has 16 divisors (see below), whose sum is σ = 715365504. Its totient is φ = 577188864.

The previous prime is 644654489. The next prime is 644654509. The reversal of 644654491 is 194456446.

It is a cyclic number.

It is not a de Polignac number, because 644654491 - 2¹ = 644654489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644654411) 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, 64375 + ... + 73711.

It is an arithmetic number, because the mean of its divisors is an integer number (44710344).

Almost surely, 2^644654491 is an apocalyptic number.

644654491 is a deficient number, since it is larger than the sum of its proper divisors (70711013).

644654491 is a wasteful number, since it uses less digits than its factorization.

644654491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9510.

The product of its digits is 414720, while the sum is 43.

The square root of 644654491 is about 25390.0470854231. The cubic root of 644654491 is about 863.8579562407.

The spelling of 644654491 in words is "six hundred forty-four million, six hundred fifty-four thousand, four hundred ninety-one".