81331472 has 10 divisors (see below), whose sum is σ = 157579758. Its totient is φ = 40665728.

The previous prime is 81331463. The next prime is 81331477. The reversal of 81331472 is 27413318.

It can be written as a sum of positive squares in only one way, i.e., 79995136 + 1336336 = 8944^2 + 1156^2 .

It is a super-2 number, since 2×81331472² = 13229616675373568, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81331477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2541593 + ... + 2541624.

Almost surely, 2^81331472 is an apocalyptic number.

It is an amenable number.

81331472 is a deficient number, since it is larger than the sum of its proper divisors (76248286).

81331472 is a wasteful number, since it uses less digits than its factorization.

81331472 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5083225 (or 5083219 counting only the distinct ones).

The product of its digits is 4032, while the sum is 29.

The square root of 81331472 is about 9018.3963097659. The cubic root of 81331472 is about 433.2642719658.

The spelling of 81331472 in words is "eighty-one million, three hundred thirty-one thousand, four hundred seventy-two".