644598947 has 2 divisors, whose sum is σ = 644598948. Its totient is φ = 644598946.

The previous prime is 644598907. The next prime is 644598949. The reversal of 644598947 is 749895446.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 644598947 - 2¹⁴ = 644582563 is a prime.

Together with 644598949, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 644598892 and 644598901.

It is not a weakly prime, because it can be changed into another prime (644598949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322299473 + 322299474.

It is an arithmetic number, because the mean of its divisors is an integer number (322299474).

Almost surely, 2^644598947 is an apocalyptic number.

644598947 is a deficient number, since it is larger than the sum of its proper divisors (1).

644598947 is an equidigital number, since it uses as much as digits as its factorization.

644598947 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8709120, while the sum is 56.

The square root of 644598947 is about 25388.9532474263. The cubic root of 644598947 is about 863.8331452734.

The spelling of 644598947 in words is "six hundred forty-four million, five hundred ninety-eight thousand, nine hundred forty-seven".