644607511 has 2 divisors, whose sum is σ = 644607512. Its totient is φ = 644607510.

The previous prime is 644607503. The next prime is 644607517. The reversal of 644607511 is 115706446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644607511 - 2³ = 644607503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644607517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322303755 + 322303756.

It is an arithmetic number, because the mean of its divisors is an integer number (322303756).

Almost surely, 2^644607511 is an apocalyptic number.

644607511 is a deficient number, since it is larger than the sum of its proper divisors (1).

644607511 is an equidigital number, since it uses as much as digits as its factorization.

644607511 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 644607511 is about 25389.1219028938. The cubic root of 644607511 is about 863.8369708223.

The spelling of 644607511 in words is "six hundred forty-four million, six hundred seven thousand, five hundred eleven".