391619971 has 2 divisors, whose sum is σ = 391619972. Its totient is φ = 391619970.

The previous prime is 391619947. The next prime is 391619981. The reversal of 391619971 is 179916193.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 391619971 - 2¹¹ = 391617923 is a prime.

It is not a weakly prime, because it can be changed into another prime (391619981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195809985 + 195809986.

It is an arithmetic number, because the mean of its divisors is an integer number (195809986).

Almost surely, 2^391619971 is an apocalyptic number.

391619971 is a deficient number, since it is larger than the sum of its proper divisors (1).

391619971 is an equidigital number, since it uses as much as digits as its factorization.

391619971 is an evil number, because the sum of its binary digits is even.

The product of its digits is 91854, while the sum is 46.

The square root of 391619971 is about 19789.3903645362. The cubic root of 391619971 is about 731.6245617455.

The spelling of 391619971 in words is "three hundred ninety-one million, six hundred nineteen thousand, nine hundred seventy-one".