81384660 has 72 divisors (see below), whose sum is σ = 282137856. Its totient is φ = 18601920.

The previous prime is 81384637. The next prime is 81384679. The reversal of 81384660 is 6648318.

It is a happy number.

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 23 ways as a sum of consecutive naturals, for example, 31036 + ... + 33555.

Almost surely, 2^81384660 is an apocalyptic number.

It is an amenable number.

81384660 is an abundant number, since it is smaller than the sum of its proper divisors (200753196).

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

81384660 is a wasteful number, since it uses less digits than its factorization.

81384660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64613 (or 64608 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 81384660 is about 9021.3446891248. The cubic root of 81384660 is about 433.3586980550.

The spelling of 81384660 in words is "eighty-one million, three hundred eighty-four thousand, six hundred sixty".