644402701 has 4 divisors (see below), whose sum is σ = 645059232. Its totient is φ = 643746172.

The previous prime is 644402623. The next prime is 644402713. The reversal of 644402701 is 107204446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 107204446 = 2 ⋅53602223.

It is a cyclic number.

It is not a de Polignac number, because 644402701 - 2⁷ = 644402573 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644402701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644402761) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 326791 + ... + 328756.

It is an arithmetic number, because the mean of its divisors is an integer number (161264808).

Almost surely, 2^644402701 is an apocalyptic number.

It is an amenable number.

644402701 is a deficient number, since it is larger than the sum of its proper divisors (656531).

644402701 is an equidigital number, since it uses as much as digits as its factorization.

644402701 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 656530.

The product of its (nonzero) digits is 5376, while the sum is 28.

The square root of 644402701 is about 25385.0881621475. The cubic root of 644402701 is about 863.7454726687.

The spelling of 644402701 in words is "six hundred forty-four million, four hundred two thousand, seven hundred one".