81367292161 has 4 divisors (see below), whose sum is σ = 81400276912. Its totient is φ = 81334307412.

The previous prime is 81367292137. The next prime is 81367292183. The reversal of 81367292161 is 16129276318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81367292161 is a prime.

It is a super-2 number, since 2×81367292161² (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 (81367292761) 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, 16488675 + ... + 16493608.

It is an arithmetic number, because the mean of its divisors is an integer number (20350069228).

Almost surely, 2^81367292161 is an apocalyptic number.

It is an amenable number.

81367292161 is a deficient number, since it is larger than the sum of its proper divisors (32984751).

81367292161 is a wasteful number, since it uses less digits than its factorization.

81367292161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32984750.

The product of its digits is 217728, while the sum is 46.

The spelling of 81367292161 in words is "eighty-one billion, three hundred sixty-seven million, two hundred ninety-two thousand, one hundred sixty-one".