644951 has 2 divisors, whose sum is σ = 644952. Its totient is φ = 644950.

The previous prime is 644933. The next prime is 644977. The reversal of 644951 is 159446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644951 - 2¹⁰ = 643927 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644951.

It is not a weakly prime, because it can be changed into another prime (644911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322475 + 322476.

It is an arithmetic number, because the mean of its divisors is an integer number (322476).

2⁶⁴⁴⁹⁵¹ is an apocalyptic number.

644951 is a deficient number, since it is larger than the sum of its proper divisors (1).

644951 is an equidigital number, since it uses as much as digits as its factorization.

644951 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 29.

The square root of 644951 is about 803.0884135635. The cubic root of 644951 is about 86.3990379837.

The spelling of 644951 in words is "six hundred forty-four thousand, nine hundred fifty-one".