25721551 has 2 divisors, whose sum is σ = 25721552. Its totient is φ = 25721550.

The previous prime is 25721543. The next prime is 25721557. The reversal of 25721551 is 15512752.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 25721551 - 2³ = 25721543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25721557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12860775 + 12860776.

It is an arithmetic number, because the mean of its divisors is an integer number (12860776).

Almost surely, 2^25721551 is an apocalyptic number.

25721551 is a deficient number, since it is larger than the sum of its proper divisors (1).

25721551 is an equidigital number, since it uses as much as digits as its factorization.

25721551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3500, while the sum is 28.

The square root of 25721551 is about 5071.6418446101. The cubic root of 25721551 is about 295.1882395256.

The spelling of 25721551 in words is "twenty-five million, seven hundred twenty-one thousand, five hundred fifty-one".