391099949 has 2 divisors, whose sum is σ = 391099950. Its totient is φ = 391099948.

The previous prime is 391099931. The next prime is 391099987. The reversal of 391099949 is 949990193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 383454724 + 7645225 = 19582^2 + 2765^2 .

It is an emirp because it is prime and its reverse (949990193) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 391099949 - 2⁸ = 391099693 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 391099949.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391099649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195549974 + 195549975.

It is an arithmetic number, because the mean of its divisors is an integer number (195549975).

Almost surely, 2^391099949 is an apocalyptic number.

It is an amenable number.

391099949 is a deficient number, since it is larger than the sum of its proper divisors (1).

391099949 is an equidigital number, since it uses as much as digits as its factorization.

391099949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 708588, while the sum is 53.

The square root of 391099949 is about 19776.2470908916. The cubic root of 391099949 is about 731.3005832104.

The spelling of 391099949 in words is "three hundred ninety-one million, ninety-nine thousand, nine hundred forty-nine".