25640645 has 8 divisors (see below), whose sum is σ = 30862104. Its totient is φ = 20450304.

The previous prime is 25640639. The next prime is 25640663. The reversal of 25640645 is 54604652.

It can be written as a sum of positive squares in 4 ways, for example, as 3869089 + 21771556 = 1967^2 + 4666^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 25640645 - 2⁶ = 25640581 is a prime.

It is a Duffinian number.

It is a congruent 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, 5924 + ... + 9293.

It is an arithmetic number, because the mean of its divisors is an integer number (3857763).

Almost surely, 2^25640645 is an apocalyptic number.

It is an amenable number.

25640645 is a deficient number, since it is larger than the sum of its proper divisors (5221459).

25640645 is a wasteful number, since it uses less digits than its factorization.

25640645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15559.

The product of its (nonzero) digits is 28800, while the sum is 32.

The square root of 25640645 is about 5063.6592499891. The cubic root of 25640645 is about 294.8784139373.

The spelling of 25640645 in words is "twenty-five million, six hundred forty thousand, six hundred forty-five".