81323239191 has 8 divisors (see below), whose sum is σ = 108438956784. Its totient is φ = 54211507200.

The previous prime is 81323239169. The next prime is 81323239213. The reversal of 81323239191 is 19193232318.

It is an interprime number because it is at equal distance from previous prime (81323239169) and next prime (81323239213).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81323239191 - 2²⁶ = 81256130327 is a prime.

It is a super-2 number, since 2×81323239191² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81323239121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 948460 + ... + 1030641.

It is an arithmetic number, because the mean of its divisors is an integer number (13554869598).

Almost surely, 2^81323239191 is an apocalyptic number.

81323239191 is a deficient number, since it is larger than the sum of its proper divisors (27115717593).

81323239191 is a wasteful number, since it uses less digits than its factorization.

81323239191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1992801.

The product of its digits is 69984, while the sum is 42.

The spelling of 81323239191 in words is "eighty-one billion, three hundred twenty-three million, two hundred thirty-nine thousand, one hundred ninety-one".