25649821 has 4 divisors (see below), whose sum is σ = 27158652. Its totient is φ = 24140992.

The previous prime is 25649783. The next prime is 25649831. The reversal of 25649821 is 12894652.

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

It can be written as a sum of positive squares in 2 ways, for example, as 20748025 + 4901796 = 4555^2 + 2214^2 .

It is a cyclic number.

It is not a de Polignac number, because 25649821 - 2⁷ = 25649693 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 (25649831) 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, 754390 + ... + 754423.

It is an arithmetic number, because the mean of its divisors is an integer number (6789663).

Almost surely, 2^25649821 is an apocalyptic number.

It is an amenable number.

25649821 is a deficient number, since it is larger than the sum of its proper divisors (1508831).

25649821 is a wasteful number, since it uses less digits than its factorization.

25649821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1508830.

The product of its digits is 34560, while the sum is 37.

The square root of 25649821 is about 5064.5652330679. The cubic root of 25649821 is about 294.9135857205.

The spelling of 25649821 in words is "twenty-five million, six hundred forty-nine thousand, eight hundred twenty-one".