391979963 has 2 divisors, whose sum is σ = 391979964. Its totient is φ = 391979962.

The previous prime is 391979957. The next prime is 391979977. The reversal of 391979963 is 369979193.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 391979963 - 2²⁸ = 123544507 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 391979899 and 391979908.

It is not a weakly prime, because it can be changed into another prime (391979933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195989981 + 195989982.

It is an arithmetic number, because the mean of its divisors is an integer number (195989982).

Almost surely, 2^391979963 is an apocalyptic number.

391979963 is a deficient number, since it is larger than the sum of its proper divisors (1).

391979963 is an equidigital number, since it uses as much as digits as its factorization.

391979963 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2480058, while the sum is 56.

The square root of 391979963 is about 19798.4838560936. The cubic root of 391979963 is about 731.8486721478.

The spelling of 391979963 in words is "three hundred ninety-one million, nine hundred seventy-nine thousand, nine hundred sixty-three".