81618252 has 12 divisors (see below), whose sum is σ = 190442616. Its totient is φ = 27206080.

The previous prime is 81618239. The next prime is 81618253. The reversal of 81618252 is 25281618.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (81618253) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3400749 + ... + 3400772.

It is an arithmetic number, because the mean of its divisors is an integer number (15870218).

Almost surely, 2^81618252 is an apocalyptic number.

It is an amenable number.

81618252 is an abundant number, since it is smaller than the sum of its proper divisors (108824364).

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

81618252 is a wasteful number, since it uses less digits than its factorization.

81618252 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6801528 (or 6801526 counting only the distinct ones).

The product of its digits is 7680, while the sum is 33.

The square root of 81618252 is about 9034.2820412028. The cubic root of 81618252 is about 433.7729138263.

The spelling of 81618252 in words is "eighty-one million, six hundred eighteen thousand, two hundred fifty-two".