68640513 has 32 divisors (see below), whose sum is σ = 97992576. Its totient is φ = 42674688.

The previous prime is 68640511. The next prime is 68640529. The reversal of 68640513 is 31504686.

It is not a de Polignac number, because 68640513 - 2¹ = 68640511 is a prime.

It is not an unprimeable number, because it can be changed into a prime (68640511) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 348331 + ... + 348527.

It is an arithmetic number, because the mean of its divisors is an integer number (3062268).

Almost surely, 2^68640513 is an apocalyptic number.

It is an amenable number.

68640513 is a deficient number, since it is larger than the sum of its proper divisors (29352063).

68640513 is a wasteful number, since it uses less digits than its factorization.

68640513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353.

The product of its (nonzero) digits is 17280, while the sum is 33.

The square root of 68640513 is about 8284.9570306671. The cubic root of 68640513 is about 409.4430530223.

It can be divided in two parts, 6864051 and 3, that multiplied together give a triangular number (20592153 = T₆₄₁₇).

The spelling of 68640513 in words is "sixty-eight million, six hundred forty thousand, five hundred thirteen".