81581764525660 has 48 divisors (see below), whose sum is σ = 195797043638784. Its totient is φ = 27970775155008.

The previous prime is 81581764525633. The next prime is 81581764525699. The reversal of 81581764525660 is 6652546718518.

It is a junction number, because it is equal to n+sod(n) for n = 81581764525592 and 81581764525601.

It is a congruent number.

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, 37162377 + ... + 39296383.

It is an arithmetic number, because the mean of its divisors is an integer number (4079105075808).

Almost surely, 2^{81581764525660} is an apocalyptic number.

It is an amenable number.

81581764525660 is an abundant number, since it is smaller than the sum of its proper divisors (114215279113124).

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

81581764525660 is a wasteful number, since it uses less digits than its factorization.

81581764525660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2407090 (or 2407088 counting only the distinct ones).

The product of its (nonzero) digits is 96768000, while the sum is 64.

The spelling of 81581764525660 in words is "eighty-one trillion, five hundred eighty-one billion, seven hundred sixty-four million, five hundred twenty-five thousand, six hundred sixty".