81285560381 has 4 divisors (see below), whose sum is σ = 83907675264. Its totient is φ = 78663445500.

The previous prime is 81285560359. The next prime is 81285560387. The reversal of 81285560381 is 18306558218.

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 not a de Polignac number, because 81285560381 - 2²² = 81281366077 is a prime.

It is a super-2 number, since 2×81285560381² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81285560387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1311057395 + ... + 1311057456.

It is an arithmetic number, because the mean of its divisors is an integer number (20976918816).

Almost surely, 2^81285560381 is an apocalyptic number.

It is an amenable number.

81285560381 is a deficient number, since it is larger than the sum of its proper divisors (2622114883).

81285560381 is a wasteful number, since it uses less digits than its factorization.

81285560381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2622114882.

The product of its (nonzero) digits is 460800, while the sum is 47.

The spelling of 81285560381 in words is "eighty-one billion, two hundred eighty-five million, five hundred sixty thousand, three hundred eighty-one".