391648819 has 2 divisors, whose sum is σ = 391648820. Its totient is φ = 391648818.

The previous prime is 391648813. The next prime is 391648841. The reversal of 391648819 is 918846193.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 391648819 - 2⁹ = 391648307 is a prime.

It is a super-2 number, since 2×391648819² = 306777594848189522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (391648813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195824409 + 195824410.

It is an arithmetic number, because the mean of its divisors is an integer number (195824410).

Almost surely, 2^391648819 is an apocalyptic number.

391648819 is a deficient number, since it is larger than the sum of its proper divisors (1).

391648819 is an equidigital number, since it uses as much as digits as its factorization.

391648819 is an evil number, because the sum of its binary digits is even.

The product of its digits is 373248, while the sum is 49.

The square root of 391648819 is about 19790.1192265231. The cubic root of 391648819 is about 731.6425259189.

The spelling of 391648819 in words is "three hundred ninety-one million, six hundred forty-eight thousand, eight hundred nineteen".