25601909997491 has 2 divisors, whose sum is σ = 25601909997492. Its totient is φ = 25601909997490.

The previous prime is 25601909997407. The next prime is 25601909997511. The reversal of 25601909997491 is 19479990910652.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25601909997491 is a prime.

It is not a weakly prime, because it can be changed into another prime (25601909997991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12800954998745 + 12800954998746.

It is an arithmetic number, because the mean of its divisors is an integer number (12800954998746).

Almost surely, 2^{25601909997491} is an apocalyptic number.

25601909997491 is a deficient number, since it is larger than the sum of its proper divisors (1).

25601909997491 is an equidigital number, since it uses as much as digits as its factorization.

25601909997491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 99202320, while the sum is 71.

The spelling of 25601909997491 in words is "twenty-five trillion, six hundred one billion, nine hundred nine million, nine hundred ninety-seven thousand, four hundred ninety-one".