81187825971 has 32 divisors (see below), whose sum is σ = 129483952128. Its totient is φ = 44241801120.

The previous prime is 81187825903. The next prime is 81187826021. The reversal of 81187825971 is 17952878118.

It is not a de Polignac number, because 81187825971 - 2¹⁰ = 81187824947 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81187823971) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 94041 + ... + 413786.

It is an arithmetic number, because the mean of its divisors is an integer number (4046373504).

Almost surely, 2^81187825971 is an apocalyptic number.

81187825971 is a deficient number, since it is larger than the sum of its proper divisors (48296126157).

81187825971 is a wasteful number, since it uses less digits than its factorization.

81187825971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508191.

The product of its digits is 2257920, while the sum is 57.

The spelling of 81187825971 in words is "eighty-one billion, one hundred eighty-seven million, eight hundred twenty-five thousand, nine hundred seventy-one".