81220872 has 16 divisors (see below), whose sum is σ = 203052240. Its totient is φ = 27073616.

The previous prime is 81220859. The next prime is 81220873. The reversal of 81220872 is 27802218.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81220873) 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, 1692078 + ... + 1692125.

It is an arithmetic number, because the mean of its divisors is an integer number (12690765).

Almost surely, 2^81220872 is an apocalyptic number.

It is an amenable number.

81220872 is an abundant number, since it is smaller than the sum of its proper divisors (121831368).

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

81220872 is a wasteful number, since it uses less digits than its factorization.

81220872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3384212 (or 3384208 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 81220872 is about 9012.2623130932. The cubic root of 81220872 is about 433.0677889198.

The spelling of 81220872 in words is "eighty-one million, two hundred twenty thousand, eight hundred seventy-two".