81431528 has 8 divisors (see below), whose sum is σ = 152684130. Its totient is φ = 40715760.

The previous prime is 81431527. The next prime is 81431563. The reversal of 81431528 is 82513418.

It can be written as a sum of positive squares in only one way, i.e., 47582404 + 33849124 = 6898^2 + 5818^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 81431494 and 81431503.

It is not an unprimeable number, because it can be changed into a prime (81431527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5089463 + ... + 5089478.

Almost surely, 2^81431528 is an apocalyptic number.

It is an amenable number.

81431528 is a deficient number, since it is larger than the sum of its proper divisors (71252602).

81431528 is a wasteful number, since it uses less digits than its factorization.

81431528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10178947 (or 10178943 counting only the distinct ones).

The product of its digits is 7680, while the sum is 32.

The square root of 81431528 is about 9023.9419324373. The cubic root of 81431528 is about 433.4418699856.

The spelling of 81431528 in words is "eighty-one million, four hundred thirty-one thousand, five hundred twenty-eight".