81912786253 has 4 divisors (see below), whose sum is σ = 82415318848. Its totient is φ = 81410253660.

The previous prime is 81912786211. The next prime is 81912786287. The reversal of 81912786253 is 35268721918.

It is a happy number.

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 81912786253 - 2²⁵ = 81879231821 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81912786253.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81912786203) 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, 251266053 + ... + 251266378.

It is an arithmetic number, because the mean of its divisors is an integer number (20603829712).

Almost surely, 2^81912786253 is an apocalyptic number.

It is an amenable number.

81912786253 is a deficient number, since it is larger than the sum of its proper divisors (502532595).

81912786253 is a wasteful number, since it uses less digits than its factorization.

81912786253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 502532594.

The product of its digits is 1451520, while the sum is 52.

The spelling of 81912786253 in words is "eighty-one billion, nine hundred twelve million, seven hundred eighty-six thousand, two hundred fifty-three".