644492887 has 2 divisors, whose sum is σ = 644492888. Its totient is φ = 644492886.

The previous prime is 644492881. The next prime is 644492917. The reversal of 644492887 is 788294446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644492887 - 2¹¹ = 644490839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644492881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322246443 + 322246444.

It is an arithmetic number, because the mean of its divisors is an integer number (322246444).

Almost surely, 2^644492887 is an apocalyptic number.

644492887 is a deficient number, since it is larger than the sum of its proper divisors (1).

644492887 is an equidigital number, since it uses as much as digits as its factorization.

644492887 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3096576, while the sum is 52.

The square root of 644492887 is about 25386.8644578254. The cubic root of 644492887 is about 863.7857653384.

The spelling of 644492887 in words is "six hundred forty-four million, four hundred ninety-two thousand, eight hundred eighty-seven".