25556021 has 2 divisors, whose sum is σ = 25556022. Its totient is φ = 25556020.

The previous prime is 25555993. The next prime is 25556053. The reversal of 25556021 is 12065552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18190225 + 7365796 = 4265^2 + 2714^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25556021 is a prime.

It is a super-2 number, since 2×25556021² = 1306220418704882, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25556071) 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 as a sum of consecutive naturals, namely, 12778010 + 12778011.

It is an arithmetic number, because the mean of its divisors is an integer number (12778011).

Almost surely, 2^25556021 is an apocalyptic number.

It is an amenable number.

25556021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25556021 is an equidigital number, since it uses as much as digits as its factorization.

25556021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3000, while the sum is 26.

The square root of 25556021 is about 5055.2963315715. The cubic root of 25556021 is about 294.5536522979.

The spelling of 25556021 in words is "twenty-five million, five hundred fifty-six thousand, twenty-one".