25640439 has 8 divisors (see below), whose sum is σ = 37295232. Its totient is φ = 15539640.

The previous prime is 25640429. The next prime is 25640453. The reversal of 25640439 is 93404652.

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

It is not a de Polignac number, because 25640439 - 2⁷ = 25640311 is a prime.

It is a super-2 number, since 2×25640439² = 1314864224225442, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 776983 = 25640439 / (2 + 5 + 6 + 4 + 0 + 4 + 3 + 9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25640429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 388459 + ... + 388524.

It is an arithmetic number, because the mean of its divisors is an integer number (4661904).

Almost surely, 2^25640439 is an apocalyptic number.

25640439 is a deficient number, since it is larger than the sum of its proper divisors (11654793).

25640439 is a wasteful number, since it uses less digits than its factorization.

25640439 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 776997.

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 25640439 is about 5063.6389089271. The cubic root of 25640439 is about 294.8776242391.

The spelling of 25640439 in words is "twenty-five million, six hundred forty thousand, four hundred thirty-nine".