81171138371 has 2 divisors, whose sum is σ = 81171138372. Its totient is φ = 81171138370.

The previous prime is 81171138329. The next prime is 81171138379. The reversal of 81171138371 is 17383117118.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81171138371 is a prime.

It is not a weakly prime, because it can be changed into another prime (81171138379) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40585569185 + 40585569186.

It is an arithmetic number, because the mean of its divisors is an integer number (40585569186).

Almost surely, 2^81171138371 is an apocalyptic number.

81171138371 is a deficient number, since it is larger than the sum of its proper divisors (1).

81171138371 is an equidigital number, since it uses as much as digits as its factorization.

81171138371 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28224, while the sum is 41.

The spelling of 81171138371 in words is "eighty-one billion, one hundred seventy-one million, one hundred thirty-eight thousand, three hundred seventy-one".