81357660 has 36 divisors (see below), whose sum is σ = 246785448. Its totient is φ = 21695328.

The previous prime is 81357623. The next prime is 81357781. The reversal of 81357660 is 6675318.

81357660 is a `hidden beast` number, since 81 + 3 + 576 + 6 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 225814 + ... + 226173.

Almost surely, 2^81357660 is an apocalyptic number.

It is an amenable number.

81357660 is an abundant number, since it is smaller than the sum of its proper divisors (165427788).

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

81357660 is a wasteful number, since it uses less digits than its factorization.

81357660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 452002 (or 451997 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The square root of 81357660 is about 9019.8481140205. The cubic root of 81357660 is about 433.3107693708.

The spelling of 81357660 in words is "eighty-one million, three hundred fifty-seven thousand, six hundred sixty".