391662889 has 2 divisors, whose sum is σ = 391662890. Its totient is φ = 391662888.

The previous prime is 391662857. The next prime is 391662911. The reversal of 391662889 is 988266193.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 224400400 + 167262489 = 14980^2 + 12933^2 .

It is an emirp because it is prime and its reverse (988266193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391662889 - 2⁵ = 391662857 is a prime.

It is not a weakly prime, because it can be changed into another prime (391662809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195831444 + 195831445.

It is an arithmetic number, because the mean of its divisors is an integer number (195831445).

Almost surely, 2^391662889 is an apocalyptic number.

It is an amenable number.

391662889 is a deficient number, since it is larger than the sum of its proper divisors (1).

391662889 is an equidigital number, since it uses as much as digits as its factorization.

391662889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1119744, while the sum is 52.

The square root of 391662889 is about 19790.4747037558. The cubic root of 391662889 is about 731.6512872433.

The spelling of 391662889 in words is "three hundred ninety-one million, six hundred sixty-two thousand, eight hundred eighty-nine".