644077505 has 8 divisors (see below), whose sum is σ = 780546024. Its totient is φ = 510160000.

The previous prime is 644077471. The next prime is 644077529. The reversal of 644077505 is 505770446.

It can be written as a sum of positive squares in 4 ways, for example, as 315453121 + 328624384 = 17761^2 + 18128^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 644077505 - 2²⁶ = 576968641 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 637196 + ... + 638205.

It is an arithmetic number, because the mean of its divisors is an integer number (97568253).

Almost surely, 2^644077505 is an apocalyptic number.

It is an amenable number.

644077505 is a deficient number, since it is larger than the sum of its proper divisors (136468519).

644077505 is a wasteful number, since it uses less digits than its factorization.

644077505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1275507.

The product of its (nonzero) digits is 117600, while the sum is 38.

The square root of 644077505 is about 25378.6820973824. The cubic root of 644077505 is about 863.6001526511.

The spelling of 644077505 in words is "six hundred forty-four million, seventy-seven thousand, five hundred five".