68711981 has 4 divisors (see below), whose sum is σ = 73997532. Its totient is φ = 63426432.

The previous prime is 68711963. The next prime is 68712001. The reversal of 68711981 is 18911786.

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 8649481 + 60062500 = 2941^2 + 7750^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-68711981 is a prime.

It is a super-2 number, since 2×68711981² = 9442672665888722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68711911) 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, 2642756 + ... + 2642781.

It is an arithmetic number, because the mean of its divisors is an integer number (18499383).

Almost surely, 2^68711981 is an apocalyptic number.

It is an amenable number.

68711981 is a deficient number, since it is larger than the sum of its proper divisors (5285551).

68711981 is a wasteful number, since it uses less digits than its factorization.

68711981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5285550.

The product of its digits is 24192, while the sum is 41.

The square root of 68711981 is about 8289.2690268805. The cubic root of 68711981 is about 409.5851067691.

The spelling of 68711981 in words is "sixty-eight million, seven hundred eleven thousand, nine hundred eighty-one".