81297513 has 20 divisors (see below), whose sum is σ = 132486288. Its totient is φ = 49270680.

The previous prime is 81297493. The next prime is 81297533. The reversal of 81297513 is 31579218.

It is an interprime number because it is at equal distance from previous prime (81297493) and next prime (81297533).

It is not a de Polignac number, because 81297513 - 2⁵ = 81297481 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81297533) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 44731 + ... + 46512.

Almost surely, 2^81297513 is an apocalyptic number.

It is an amenable number.

81297513 is a deficient number, since it is larger than the sum of its proper divisors (51188775).

81297513 is a wasteful number, since it uses less digits than its factorization.

81297513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91266 (or 91257 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 81297513 is about 9016.5133505142. The cubic root of 81297513 is about 433.2039621034.

It can be divided in two parts, 81297 and 513, that added together give a triangular number (81810 = T₄₀₄).

The spelling of 81297513 in words is "eighty-one million, two hundred ninety-seven thousand, five hundred thirteen".