81537081648 has 80 divisors (see below), whose sum is σ = 229832777856. Its totient is φ = 24703211520.

The previous prime is 81537081629. The next prime is 81537081653. The reversal of 81537081648 is 84618073518.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81537081648.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3241536 + ... + 3266592.

Almost surely, 2^81537081648 is an apocalyptic number.

81537081648 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

81537081648 is an abundant number, since it is smaller than the sum of its proper divisors (148295696208).

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

81537081648 is a wasteful number, since it uses less digits than its factorization.

81537081648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31242 (or 31236 counting only the distinct ones).

The product of its (nonzero) digits is 1290240, while the sum is 51.

The spelling of 81537081648 in words is "eighty-one billion, five hundred thirty-seven million, eighty-one thousand, six hundred forty-eight".