25040856721 has 2 divisors, whose sum is σ = 25040856722. Its totient is φ = 25040856720.

The previous prime is 25040856691. The next prime is 25040856761. The reversal of 25040856721 is 12765804052.

It is an a-pointer prime, because the next prime (25040856761) can be obtained adding 25040856721 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21982213696 + 3058643025 = 148264^2 + 55305^2 .

It is a cyclic number.

It is not a de Polignac number, because 25040856721 - 2⁷ = 25040856593 is a prime.

It is not a weakly prime, because it can be changed into another prime (25040856761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12520428360 + 12520428361.

It is an arithmetic number, because the mean of its divisors is an integer number (12520428361).

Almost surely, 2^25040856721 is an apocalyptic number.

It is an amenable number.

25040856721 is a deficient number, since it is larger than the sum of its proper divisors (1).

25040856721 is an equidigital number, since it uses as much as digits as its factorization.

25040856721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 134400, while the sum is 40.

The spelling of 25040856721 in words is "twenty-five billion, forty million, eight hundred fifty-six thousand, seven hundred twenty-one".