644472187 has 2 divisors, whose sum is σ = 644472188. Its totient is φ = 644472186.

The previous prime is 644472161. The next prime is 644472197. The reversal of 644472187 is 781274446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644472187 - 2²³ = 636083579 is a prime.

It is not a weakly prime, because it can be changed into another prime (644472197) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322236093 + 322236094.

It is an arithmetic number, because the mean of its divisors is an integer number (322236094).

Almost surely, 2^644472187 is an apocalyptic number.

644472187 is a deficient number, since it is larger than the sum of its proper divisors (1).

644472187 is an equidigital number, since it uses as much as digits as its factorization.

644472187 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 301056, while the sum is 43.

The square root of 644472187 is about 25386.4567634004. The cubic root of 644472187 is about 863.7765174697.

The spelling of 644472187 in words is "six hundred forty-four million, four hundred seventy-two thousand, one hundred eighty-seven".