644270025 has 24 divisors (see below), whose sum is σ = 1217364544. Its totient is φ = 294523200.

The previous prime is 644270017. The next prime is 644270027. The reversal of 644270025 is 520072446.

It is not a de Polignac number, because 644270025 - 2³ = 644270017 is a prime.

It is a super-2 number, since 2×644270025² = 830167730227001250, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 644269974 and 644270001.

It is not an unprimeable number, because it can be changed into a prime (644270027) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 613066 + ... + 614115.

Almost surely, 2^644270025 is an apocalyptic number.

It is an amenable number.

644270025 is a deficient number, since it is larger than the sum of its proper divisors (573094519).

644270025 is a wasteful number, since it uses less digits than its factorization.

644270025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1227201 (or 1227196 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 30.

The square root of 644270025 is about 25382.4747611418. The cubic root of 644270025 is about 863.6861897804.

It can be divided in two parts, 6442 and 70025, that added together give a palindrome (76467).

The spelling of 644270025 in words is "six hundred forty-four million, two hundred seventy thousand, twenty-five".