81115035891 has 32 divisors (see below), whose sum is σ = 112456243200. Its totient is φ = 51951456000.

The previous prime is 81115035823. The next prime is 81115035899. The reversal of 81115035891 is 19853051118.

It is a de Polignac number, because none of the positive numbers 2^k-81115035891 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81115035899) 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, 15899241 + ... + 15904341.

It is an arithmetic number, because the mean of its divisors is an integer number (3514257600).

Almost surely, 2^81115035891 is an apocalyptic number.

81115035891 is a deficient number, since it is larger than the sum of its proper divisors (31341207309).

81115035891 is a wasteful number, since it uses less digits than its factorization.

81115035891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6347.

The product of its (nonzero) digits is 43200, while the sum is 42.

The spelling of 81115035891 in words is "eighty-one billion, one hundred fifteen million, thirty-five thousand, eight hundred ninety-one".