81071921077 has 16 divisors (see below), whose sum is σ = 95462410752. Its totient is φ = 67409798400.

The previous prime is 81071921023. The next prime is 81071921083. The reversal of 81071921077 is 77012917018.

It is not a de Polignac number, because 81071921077 - 2²³ = 81063532469 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81071921017) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1053174 + ... + 1127527.

It is an arithmetic number, because the mean of its divisors is an integer number (5966400672).

Almost surely, 2^81071921077 is an apocalyptic number.

It is an amenable number.

81071921077 is a deficient number, since it is larger than the sum of its proper divisors (14390489675).

81071921077 is a wasteful number, since it uses less digits than its factorization.

81071921077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2180868.

The product of its (nonzero) digits is 49392, while the sum is 43.

The spelling of 81071921077 in words is "eighty-one billion, seventy-one million, nine hundred twenty-one thousand, seventy-seven".