81947674891 has 2 divisors, whose sum is σ = 81947674892. Its totient is φ = 81947674890.

The previous prime is 81947674843. The next prime is 81947674909. The reversal of 81947674891 is 19847674918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81947674891 - 2¹⁵ = 81947642123 is a prime.

It is not a weakly prime, because it can be changed into another prime (81947674801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40973837445 + 40973837446.

It is an arithmetic number, because the mean of its divisors is an integer number (40973837446).

Almost surely, 2^81947674891 is an apocalyptic number.

81947674891 is a deficient number, since it is larger than the sum of its proper divisors (1).

81947674891 is an equidigital number, since it uses as much as digits as its factorization.

81947674891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24385536, while the sum is 64.

The spelling of 81947674891 in words is "eighty-one billion, nine hundred forty-seven million, six hundred seventy-four thousand, eight hundred ninety-one".