81991274425 has 12 divisors (see below), whose sum is σ = 105175015020. Its totient is φ = 63331190720.

The previous prime is 81991274423. The next prime is 81991274531. The reversal of 81991274425 is 52447219918.

It can be written as a sum of positive squares in 6 ways, for example, as 302203456 + 81689070969 = 17384^2 + 285813^2 .

It is not a de Polignac number, because 81991274425 - 2¹ = 81991274423 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81991274423) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 56544982 + ... + 56546431.

It is an arithmetic number, because the mean of its divisors is an integer number (8764584585).

Almost surely, 2^81991274425 is an apocalyptic number.

It is an amenable number.

81991274425 is a deficient number, since it is larger than the sum of its proper divisors (23183740595).

81991274425 is a wasteful number, since it uses less digits than its factorization.

81991274425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113091452 (or 113091447 counting only the distinct ones).

The product of its digits is 1451520, while the sum is 52.

The spelling of 81991274425 in words is "eighty-one billion, nine hundred ninety-one million, two hundred seventy-four thousand, four hundred twenty-five".