644965187 has 2 divisors, whose sum is σ = 644965188. Its totient is φ = 644965186.

The previous prime is 644965141. The next prime is 644965253. The reversal of 644965187 is 781569446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644965187 - 2¹⁴ = 644948803 is a prime.

It is not a weakly prime, because it can be changed into another prime (644965487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322482593 + 322482594.

It is an arithmetic number, because the mean of its divisors is an integer number (322482594).

Almost surely, 2^644965187 is an apocalyptic number.

644965187 is a deficient number, since it is larger than the sum of its proper divisors (1).

644965187 is an equidigital number, since it uses as much as digits as its factorization.

644965187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 50.

The square root of 644965187 is about 25396.1648088840. The cubic root of 644965187 is about 863.9967148616.

The spelling of 644965187 in words is "six hundred forty-four million, nine hundred sixty-five thousand, one hundred eighty-seven".