25721251 has 2 divisors, whose sum is σ = 25721252. Its totient is φ = 25721250.

The previous prime is 25721239. The next prime is 25721257. The reversal of 25721251 is 15212752.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25721251 is a prime.

It is equal to p_1608163 and since 25721251 and 1608163 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (25721257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12860625 + 12860626.

It is an arithmetic number, because the mean of its divisors is an integer number (12860626).

Almost surely, 2^25721251 is an apocalyptic number.

25721251 is a deficient number, since it is larger than the sum of its proper divisors (1).

25721251 is an equidigital number, since it uses as much as digits as its factorization.

25721251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1400, while the sum is 25.

The square root of 25721251 is about 5071.6122683029. The cubic root of 25721251 is about 295.1870918911.

The spelling of 25721251 in words is "twenty-five million, seven hundred twenty-one thousand, two hundred fifty-one".