25649 has 4 divisors (see below), whose sum is σ = 27636. Its totient is φ = 23664.

The previous prime is 25643. The next prime is 25657. The reversal of 25649 is 94652.

25649 = 18² + 19² + ... + 43².

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 4624 + 21025 = 68^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 25649 - 2⁴ = 25633 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a nialpdrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (25643) 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, 974 + ... + 999.

It is an arithmetic number, because the mean of its divisors is an integer number (6909).

2²⁵⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

25649 is a deficient number, since it is larger than the sum of its proper divisors (1987).

25649 is a wasteful number, since it uses less digits than its factorization.

25649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1986.

The product of its digits is 2160, while the sum is 26.

The square root of 25649 is about 160.1530517973. The cubic root of 25649 is about 29.4910439154.

It can be divided in two parts, 256 and 49, that multiplied together give a square (12544 = 112²).

The spelling of 25649 in words is "twenty-five thousand, six hundred forty-nine".