81997110731 has 2 divisors, whose sum is σ = 81997110732. Its totient is φ = 81997110730.

The previous prime is 81997110703. The next prime is 81997110743. The reversal of 81997110731 is 13701179918.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81997110731 is a prime.

It is a super-2 number, since 2×81997110731² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81997110761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40998555365 + 40998555366.

It is an arithmetic number, because the mean of its divisors is an integer number (40998555366).

Almost surely, 2^81997110731 is an apocalyptic number.

81997110731 is a deficient number, since it is larger than the sum of its proper divisors (1).

81997110731 is an equidigital number, since it uses as much as digits as its factorization.

81997110731 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 95256, while the sum is 47.

The spelling of 81997110731 in words is "eighty-one billion, nine hundred ninety-seven million, one hundred ten thousand, seven hundred thirty-one".