81985380 has 48 divisors (see below), whose sum is σ = 241644480. Its totient is φ = 20711808.

The previous prime is 81985369. The next prime is 81985427. The reversal of 81985380 is 8358918.

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, 34819 + ... + 37098.

It is an arithmetic number, because the mean of its divisors is an integer number (5034260).

Almost surely, 2^81985380 is an apocalyptic number.

It is an amenable number.

81985380 is an abundant number, since it is smaller than the sum of its proper divisors (159659100).

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

81985380 is a wasteful number, since it uses less digits than its factorization.

81985380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71948 (or 71946 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 42.

The square root of 81985380 is about 9054.5778476967. The cubic root of 81985380 is about 434.4223274002.

The spelling of 81985380 in words is "eighty-one million, nine hundred eighty-five thousand, three hundred eighty".