81215018504 has 16 divisors (see below), whose sum is σ = 153848039100. Its totient is φ = 40188874752.

The previous prime is 81215018497. The next prime is 81215018509. The reversal of 81215018504 is 40581051218.

It can be written as a sum of positive squares in 2 ways, for example, as 80371116004 + 843902500 = 283498^2 + 29050^2 .

It is not an unprimeable number, because it can be changed into a prime (81215018509) 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, 52328489 + ... + 52330040.

Almost surely, 2^81215018504 is an apocalyptic number.

It is an amenable number.

81215018504 is a deficient number, since it is larger than the sum of its proper divisors (72633020596).

81215018504 is a wasteful number, since it uses less digits than its factorization.

81215018504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104658632 (or 104658628 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 35.

The spelling of 81215018504 in words is "eighty-one billion, two hundred fifteen million, eighteen thousand, five hundred four".