81310397116921 has 12 divisors (see below), whose sum is σ = 94592959418880. Its totient is φ = 69689176839240.

The previous prime is 81310397116853. The next prime is 81310397116933. The reversal of 81310397116921 is 12961179301318.

It is a happy number.

It is not a de Polignac number, because 81310397116921 - 2¹³ = 81310397108729 is a prime.

It is a super-2 number, since 2×81310397116921² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81310397116621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 64239001 + ... + 65492518.

It is an arithmetic number, because the mean of its divisors is an integer number (7882746618240).

Almost surely, 2^{81310397116921} is an apocalyptic number.

It is an amenable number.

81310397116921 is a deficient number, since it is larger than the sum of its proper divisors (13282562301959).

81310397116921 is a wasteful number, since it uses less digits than its factorization.

81310397116921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129744324 (or 129744317 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 52.

The spelling of 81310397116921 in words is "eighty-one trillion, three hundred ten billion, three hundred ninety-seven million, one hundred sixteen thousand, nine hundred twenty-one".