81291874379 has 4 divisors (see below), whose sum is σ = 81646860960. Its totient is φ = 80936887800.

The previous prime is 81291874333. The next prime is 81291874381. The reversal of 81291874379 is 97347819218.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81291874379 - 2³² = 76996907083 is a prime.

It is a super-2 number, since 2×81291874379² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81291874679) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 177492947 + ... + 177493404.

It is an arithmetic number, because the mean of its divisors is an integer number (20411715240).

Almost surely, 2^81291874379 is an apocalyptic number.

81291874379 is a deficient number, since it is larger than the sum of its proper divisors (354986581).

81291874379 is a wasteful number, since it uses less digits than its factorization.

81291874379 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354986580.

The product of its digits is 6096384, while the sum is 59.

The spelling of 81291874379 in words is "eighty-one billion, two hundred ninety-one million, eight hundred seventy-four thousand, three hundred seventy-nine".