25638649 has 2 divisors, whose sum is σ = 25638650. Its totient is φ = 25638648.

The previous prime is 25638647. The next prime is 25638673. The reversal of 25638649 is 94683652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25452025 + 186624 = 5045^2 + 432^2 .

It is a cyclic number.

It is not a de Polignac number, because 25638649 - 2¹ = 25638647 is a prime.

Together with 25638647, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (25638647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12819324 + 12819325.

It is an arithmetic number, because the mean of its divisors is an integer number (12819325).

Almost surely, 2^25638649 is an apocalyptic number.

It is an amenable number.

25638649 is a deficient number, since it is larger than the sum of its proper divisors (1).

25638649 is an equidigital number, since it uses as much as digits as its factorization.

25638649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 43.

The square root of 25638649 is about 5063.4621554822. The cubic root of 25638649 is about 294.8707621201.

The spelling of 25638649 in words is "twenty-five million, six hundred thirty-eight thousand, six hundred forty-nine".