25655721 has 24 divisors (see below), whose sum is σ = 42338880. Its totient is φ = 13530816.

The previous prime is 25655699. The next prime is 25655731. The reversal of 25655721 is 12755652.

It is not a de Polignac number, because 25655721 - 2⁹ = 25655209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (25655731) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 66 + ... + 7163.

It is an arithmetic number, because the mean of its divisors is an integer number (1764120).

Almost surely, 2^25655721 is an apocalyptic number.

25655721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

25655721 is a deficient number, since it is larger than the sum of its proper divisors (16683159).

25655721 is a wasteful number, since it uses less digits than its factorization.

25655721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7265 (or 7252 counting only the distinct ones).

The product of its digits is 21000, while the sum is 33.

The square root of 25655721 is about 5065.1476780051. The cubic root of 25655721 is about 294.9361961026.

The spelling of 25655721 in words is "twenty-five million, six hundred fifty-five thousand, seven hundred twenty-one".