68661891 has 8 divisors (see below), whose sum is σ = 101721360. Its totient is φ = 45774576.

The previous prime is 68661889. The next prime is 68661893. The reversal of 68661891 is 19816686.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (68661889) and next prime (68661893).

It is not a de Polignac number, because 68661891 - 2¹ = 68661889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (68661893) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1271490 + ... + 1271543.

It is an arithmetic number, because the mean of its divisors is an integer number (12715170).

Almost surely, 2^68661891 is an apocalyptic number.

68661891 is a deficient number, since it is larger than the sum of its proper divisors (33059469).

68661891 is a wasteful number, since it uses less digits than its factorization.

68661891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2543042 (or 2543036 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 68661891 is about 8286.2470998637. The cubic root of 68661891 is about 409.4855554486.

The spelling of 68661891 in words is "sixty-eight million, six hundred sixty-one thousand, eight hundred ninety-one".