81261986584 has 16 divisors (see below), whose sum is σ = 152797862520. Its totient is φ = 40515889920.

The previous prime is 81261986579. The next prime is 81261986587. The reversal of 81261986584 is 48568916218.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81261986587) 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, 14384922 + ... + 14390569.

Almost surely, 2^81261986584 is an apocalyptic number.

It is an amenable number.

81261986584 is a deficient number, since it is larger than the sum of its proper divisors (71535875936).

81261986584 is a wasteful number, since it uses less digits than its factorization.

81261986584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28775850 (or 28775846 counting only the distinct ones).

The product of its digits is 6635520, while the sum is 58.

The spelling of 81261986584 in words is "eighty-one billion, two hundred sixty-one million, nine hundred eighty-six thousand, five hundred eighty-four".