391081649 has 4 divisors (see below), whose sum is σ = 446950464. Its totient is φ = 335212836.

The previous prime is 391081637. The next prime is 391081661. The reversal of 391081649 is 946180193.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (391081637) and next prime (391081661).

It is not a de Polignac number, because 391081649 - 2²⁰ = 390033073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (391081609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27934397 + ... + 27934410.

It is an arithmetic number, because the mean of its divisors is an integer number (111737616).

Almost surely, 2^391081649 is an apocalyptic number.

It is an amenable number.

391081649 is a deficient number, since it is larger than the sum of its proper divisors (55868815).

391081649 is an equidigital number, since it uses as much as digits as its factorization.

391081649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55868814.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 391081649 is about 19775.7844092213. The cubic root of 391081649 is about 731.2891769110.

The spelling of 391081649 in words is "three hundred ninety-one million, eighty-one thousand, six hundred forty-nine".