81332454391 has 32 divisors (see below), whose sum is σ = 93240778752. Its totient is φ = 70542420480.

The previous prime is 81332454389. The next prime is 81332454431. The reversal of 81332454391 is 19345423318.

It is a cyclic number.

It is not a de Polignac number, because 81332454391 - 2¹ = 81332454389 is a prime.

It is a super-2 number, since 2×81332454391² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81332454331) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 872080 + ... + 960826.

It is an arithmetic number, because the mean of its divisors is an integer number (2913774336).

Almost surely, 2^81332454391 is an apocalyptic number.

81332454391 is a deficient number, since it is larger than the sum of its proper divisors (11908324361).

81332454391 is a wasteful number, since it uses less digits than its factorization.

81332454391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88879.

The product of its digits is 311040, while the sum is 43.

The spelling of 81332454391 in words is "eighty-one billion, three hundred thirty-two million, four hundred fifty-four thousand, three hundred ninety-one".