68138513 has 4 divisors (see below), whose sum is σ = 68169780. Its totient is φ = 68107248.

The previous prime is 68138509. The next prime is 68138561. The reversal of 68138513 is 31583186.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 47499664 + 20638849 = 6892^2 + 4543^2 .

It is a cyclic number.

It is not a de Polignac number, because 68138513 - 2² = 68138509 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68138573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12098 + ... + 16811.

It is an arithmetic number, because the mean of its divisors is an integer number (17042445).

Almost surely, 2^68138513 is an apocalyptic number.

It is an amenable number.

68138513 is a deficient number, since it is larger than the sum of its proper divisors (31267).

68138513 is a wasteful number, since it uses less digits than its factorization.

68138513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31266.

The product of its digits is 17280, while the sum is 35.

The square root of 68138513 is about 8254.6055629570. The cubic root of 68138513 is about 408.4424606105.

The spelling of 68138513 in words is "sixty-eight million, one hundred thirty-eight thousand, five hundred thirteen".