81675697591 has 2 divisors, whose sum is σ = 81675697592. Its totient is φ = 81675697590.

The previous prime is 81675697589. The next prime is 81675697603. The reversal of 81675697591 is 19579657618.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81675697591 - 2¹ = 81675697589 is a prime.

Together with 81675697589, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81675697291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40837848795 + 40837848796.

It is an arithmetic number, because the mean of its divisors is an integer number (40837848796).

Almost surely, 2^81675697591 is an apocalyptic number.

81675697591 is a deficient number, since it is larger than the sum of its proper divisors (1).

81675697591 is an equidigital number, since it uses as much as digits as its factorization.

81675697591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28576800, while the sum is 64.

The spelling of 81675697591 in words is "eighty-one billion, six hundred seventy-five million, six hundred ninety-seven thousand, five hundred ninety-one".