25640247 has 4 divisors (see below), whose sum is σ = 34187000. Its totient is φ = 17093496.

The previous prime is 25640227. The next prime is 25640249. The reversal of 25640247 is 74204652.

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

It is not a de Polignac number, because 25640247 - 2⁶ = 25640183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25640249) 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, 4273372 + ... + 4273377.

It is an arithmetic number, because the mean of its divisors is an integer number (8546750).

Almost surely, 2^25640247 is an apocalyptic number.

25640247 is a deficient number, since it is larger than the sum of its proper divisors (8546753).

25640247 is an equidigital number, since it uses as much as digits as its factorization.

25640247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8546752.

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

The square root of 25640247 is about 5063.6199501937. The cubic root of 25640247 is about 294.8768882059.

Adding to 25640247 its reverse (74204652), we get a palindrome (99844899).

The spelling of 25640247 in words is "twenty-five million, six hundred forty thousand, two hundred forty-seven".