81018974453761 has 4 divisors (see below), whose sum is σ = 82228212878512. Its totient is φ = 79809736029012.

The previous prime is 81018974453759. The next prime is 81018974453783. The reversal of 81018974453761 is 16735447981018.

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 81018974453761 - 2¹ = 81018974453759 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81018974453693 and 81018974453702.

It is not an unprimeable number, because it can be changed into a prime (81018974453161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 604619212275 + ... + 604619212408.

It is an arithmetic number, because the mean of its divisors is an integer number (20557053219628).

Almost surely, 2^{81018974453761} is an apocalyptic number.

It is an amenable number.

81018974453761 is a deficient number, since it is larger than the sum of its proper divisors (1209238424751).

81018974453761 is a wasteful number, since it uses less digits than its factorization.

81018974453761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209238424750.

The product of its (nonzero) digits is 40642560, while the sum is 64.

The spelling of 81018974453761 in words is "eighty-one trillion, eighteen billion, nine hundred seventy-four million, four hundred fifty-three thousand, seven hundred sixty-one".