81461406791 has 4 divisors (see below), whose sum is σ = 83663066472. Its totient is φ = 79259747112.

The previous prime is 81461406751. The next prime is 81461406809. The reversal of 81461406791 is 19760416418.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19760416418 = 2 ⋅9880208209.

It is a cyclic number.

It is not a de Polignac number, because 81461406791 - 2⁶ = 81461406727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81461406751) 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, 1100829785 + ... + 1100829858.

It is an arithmetic number, because the mean of its divisors is an integer number (20915766618).

Almost surely, 2^81461406791 is an apocalyptic number.

81461406791 is a deficient number, since it is larger than the sum of its proper divisors (2201659681).

81461406791 is a wasteful number, since it uses less digits than its factorization.

81461406791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2201659680.

The product of its (nonzero) digits is 290304, while the sum is 47.

The spelling of 81461406791 in words is "eighty-one billion, four hundred sixty-one million, four hundred six thousand, seven hundred ninety-one".