81364246657 has 4 divisors (see below), whose sum is σ = 81390186756. Its totient is φ = 81338306560.

The previous prime is 81364246637. The next prime is 81364246681. The reversal of 81364246657 is 75664246318.

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

It can be written as a sum of positive squares in 2 ways, for example, as 73116700801 + 8247545856 = 270401^2 + 90816^2 .

It is a cyclic number.

It is not a de Polignac number, because 81364246657 - 2⁷ = 81364246529 is a prime.

It is a super-2 number, since 2×81364246657² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81364246637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12965344 + ... + 12971617.

It is an arithmetic number, because the mean of its divisors is an integer number (20347546689).

Almost surely, 2^81364246657 is an apocalyptic number.

It is an amenable number.

81364246657 is a deficient number, since it is larger than the sum of its proper divisors (25940099).

81364246657 is a wasteful number, since it uses less digits than its factorization.

81364246657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25940098.

The product of its digits is 5806080, while the sum is 52.

The spelling of 81364246657 in words is "eighty-one billion, three hundred sixty-four million, two hundred forty-six thousand, six hundred fifty-seven".