81275493634921 has 4 divisors (see below), whose sum is σ = 81276108173392. Its totient is φ = 81274879096452.

The previous prime is 81275493634861. The next prime is 81275493634961. The reversal of 81275493634921 is 12943639457218.

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 not a de Polignac number, because 81275493634921 - 2³³ = 81266903700329 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81275493634961) 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, 307070811 + ... + 307335376.

It is an arithmetic number, because the mean of its divisors is an integer number (20319027043348).

Almost surely, 2^{81275493634921} is an apocalyptic number.

It is an amenable number.

81275493634921 is a deficient number, since it is larger than the sum of its proper divisors (614538471).

81275493634921 is a wasteful number, since it uses less digits than its factorization.

81275493634921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 614538470.

The product of its digits is 78382080, while the sum is 64.

The spelling of 81275493634921 in words is "eighty-one trillion, two hundred seventy-five billion, four hundred ninety-three million, six hundred thirty-four thousand, nine hundred twenty-one".