81916941994 has 4 divisors (see below), whose sum is σ = 122875412994. Its totient is φ = 40958470996.

The previous prime is 81916941991. The next prime is 81916942001. The reversal of 81916941994 is 49914961918.

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

It can be written as a sum of positive squares in only one way, i.e., 71500086025 + 10416855969 = 267395^2 + 102063^2 .

It is not an unprimeable number, because it can be changed into a prime (81916941991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20479235497 + ... + 20479235500.

Almost surely, 2^81916941994 is an apocalyptic number.

81916941994 is a deficient number, since it is larger than the sum of its proper divisors (40958471000).

81916941994 is a wasteful number, since it uses less digits than its factorization.

81916941994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40958470999.

The product of its digits is 5038848, while the sum is 61.

The spelling of 81916941994 in words is "eighty-one billion, nine hundred sixteen million, nine hundred forty-one thousand, nine hundred ninety-four".