81310522051 has 4 divisors (see below), whose sum is σ = 88702387704. Its totient is φ = 73918656400.

The previous prime is 81310522043. The next prime is 81310522063. The reversal of 81310522051 is 15022501318.

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

It is a cyclic number.

It is not a de Polignac number, because 81310522051 - 2³ = 81310522043 is a prime.

It is a super-2 number, since 2×81310522051² (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 (81310522031) 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, 3695932810 + ... + 3695932831.

It is an arithmetic number, because the mean of its divisors is an integer number (22175596926).

Almost surely, 2^81310522051 is an apocalyptic number.

81310522051 is a deficient number, since it is larger than the sum of its proper divisors (7391865653).

81310522051 is a wasteful number, since it uses less digits than its factorization.

81310522051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7391865652.

The product of its (nonzero) digits is 2400, while the sum is 28.

The spelling of 81310522051 in words is "eighty-one billion, three hundred ten million, five hundred twenty-two thousand, fifty-one".