391388971 has 2 divisors, whose sum is σ = 391388972. Its totient is φ = 391388970.

The previous prime is 391388969. The next prime is 391388983. The reversal of 391388971 is 179883193.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 391388971 - 2¹ = 391388969 is a prime.

Together with 391388969, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (391388951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195694485 + 195694486.

It is an arithmetic number, because the mean of its divisors is an integer number (195694486).

Almost surely, 2^391388971 is an apocalyptic number.

391388971 is a deficient number, since it is larger than the sum of its proper divisors (1).

391388971 is an equidigital number, since it uses as much as digits as its factorization.

391388971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 49.

The square root of 391388971 is about 19783.5530428687. The cubic root of 391388971 is about 731.4806820264.

The spelling of 391388971 in words is "three hundred ninety-one million, three hundred eighty-eight thousand, nine hundred seventy-one".