25643257 has 4 divisors (see below), whose sum is σ = 26336356. Its totient is φ = 24950160.

The previous prime is 25643251. The next prime is 25643263. The reversal of 25643257 is 75234652.

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

It is an interprime number because it is at equal distance from previous prime (25643251) and next prime (25643263).

It can be written as a sum of positive squares in 2 ways, for example, as 24364096 + 1279161 = 4936^2 + 1131^2 .

It is a cyclic number.

It is not a de Polignac number, because 25643257 - 2¹⁵ = 25610489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25643251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 346494 + ... + 346567.

It is an arithmetic number, because the mean of its divisors is an integer number (6584089).

Almost surely, 2^25643257 is an apocalyptic number.

It is an amenable number.

25643257 is a deficient number, since it is larger than the sum of its proper divisors (693099).

25643257 is an equidigital number, since it uses as much as digits as its factorization.

25643257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 693098.

The product of its digits is 50400, while the sum is 34.

The square root of 25643257 is about 5063.9171596700. The cubic root of 25643257 is about 294.8884266374. Note that the first 3 decimals are identical.

The spelling of 25643257 in words is "twenty-five million, six hundred forty-three thousand, two hundred fifty-seven".