644670271 has 4 divisors (see below), whose sum is σ = 736766032. Its totient is φ = 552574512.

The previous prime is 644670269. The next prime is 644670281. The reversal of 644670271 is 172076446.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 644670271 - 2¹ = 644670269 is a prime.

It is a super-2 number, since 2×644670271² = 831199516622426882, which contains 22 as substring.

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 644670271.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644670211) 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, 46047870 + ... + 46047883.

It is an arithmetic number, because the mean of its divisors is an integer number (184191508).

Almost surely, 2^644670271 is an apocalyptic number.

644670271 is a deficient number, since it is larger than the sum of its proper divisors (92095761).

644670271 is an equidigital number, since it uses as much as digits as its factorization.

644670271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92095760.

The product of its (nonzero) digits is 56448, while the sum is 37.

The square root of 644670271 is about 25390.3578352098. The cubic root of 644670271 is about 863.8650047540.

The spelling of 644670271 in words is "six hundred forty-four million, six hundred seventy thousand, two hundred seventy-one".