81691049267 has 2 divisors, whose sum is σ = 81691049268. Its totient is φ = 81691049266.

The previous prime is 81691049201. The next prime is 81691049287. The reversal of 81691049267 is 76294019618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81691049267 - 2²⁴ = 81674272051 is a prime.

It is not a weakly prime, because it can be changed into another prime (81691049287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40845524633 + 40845524634.

It is an arithmetic number, because the mean of its divisors is an integer number (40845524634).

Almost surely, 2^81691049267 is an apocalyptic number.

81691049267 is a deficient number, since it is larger than the sum of its proper divisors (1).

81691049267 is an equidigital number, since it uses as much as digits as its factorization.

81691049267 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1306368, while the sum is 53.

The spelling of 81691049267 in words is "eighty-one billion, six hundred ninety-one million, forty-nine thousand, two hundred sixty-seven".