81817072 has 20 divisors (see below), whose sum is σ = 165413520. Its totient is φ = 39129728.

The previous prime is 81817069. The next prime is 81817081. The reversal of 81817072 is 27071818.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 110797 + ... + 111532.

It is an arithmetic number, because the mean of its divisors is an integer number (8270676).

Almost surely, 2^81817072 is an apocalyptic number.

It is an amenable number.

81817072 is an abundant number, since it is smaller than the sum of its proper divisors (83596448).

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

81817072 is a wasteful number, since it uses less digits than its factorization.

81817072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222360 (or 222354 counting only the distinct ones).

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 81817072 is about 9045.2789896166. The cubic root of 81817072 is about 434.1248481664.

The spelling of 81817072 in words is "eighty-one million, eight hundred seventeen thousand, seventy-two".