81015156881 has 2 divisors, whose sum is σ = 81015156882. Its totient is φ = 81015156880.

The previous prime is 81015156857. The next prime is 81015156889. The reversal of 81015156881 is 18865151018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62940774400 + 18074382481 = 250880^2 + 134441^2 .

It is a cyclic number.

It is not a de Polignac number, because 81015156881 - 2²² = 81010962577 is a prime.

It is a super-2 number, since 2×81015156881² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81015156889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40507578440 + 40507578441.

It is an arithmetic number, because the mean of its divisors is an integer number (40507578441).

Almost surely, 2^81015156881 is an apocalyptic number.

It is an amenable number.

81015156881 is a deficient number, since it is larger than the sum of its proper divisors (1).

81015156881 is an equidigital number, since it uses as much as digits as its factorization.

81015156881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 76800, while the sum is 44.

The spelling of 81015156881 in words is "eighty-one billion, fifteen million, one hundred fifty-six thousand, eight hundred eighty-one".