66731288891 has 2 divisors, whose sum is σ = 66731288892. Its totient is φ = 66731288890.

The previous prime is 66731288867. The next prime is 66731288989. The reversal of 66731288891 is 19888213766.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66731288891 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66731288891.

It is not a weakly prime, because it can be changed into another prime (66731285891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33365644445 + 33365644446.

It is an arithmetic number, because the mean of its divisors is an integer number (33365644446).

Almost surely, 2^66731288891 is an apocalyptic number.

66731288891 is a deficient number, since it is larger than the sum of its proper divisors (1).

66731288891 is an equidigital number, since it uses as much as digits as its factorization.

66731288891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6967296, while the sum is 59.

The spelling of 66731288891 in words is "sixty-six billion, seven hundred thirty-one million, two hundred eighty-eight thousand, eight hundred ninety-one".