81263618868 has 24 divisors (see below), whose sum is σ = 199594853920. Its totient is φ = 25662195360.

The previous prime is 81263618833. The next prime is 81263618921. The reversal of 81263618868 is 86881636218.

It is a happy number.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 178209463 + ... + 178209918.

Almost surely, 2^81263618868 is an apocalyptic number.

It is an amenable number.

81263618868 is an abundant number, since it is smaller than the sum of its proper divisors (118331235052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81263618868 is a wasteful number, since it uses less digits than its factorization.

81263618868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 356419407 (or 356419405 counting only the distinct ones).

The product of its digits is 5308416, while the sum is 57.

The spelling of 81263618868 in words is "eighty-one billion, two hundred sixty-three million, six hundred eighteen thousand, eight hundred sixty-eight".