391921345 has 4 divisors (see below), whose sum is σ = 470305620. Its totient is φ = 313537072.

The previous prime is 391921339. The next prime is 391921351. The reversal of 391921345 is 543129193.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (391921339) and next prime (391921351).

It can be written as a sum of positive squares in 2 ways, for example, as 266570929 + 125350416 = 16327^2 + 11196^2 .

It is a cyclic number.

It is not a de Polignac number, because 391921345 - 2⁷ = 391921217 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39192130 + ... + 39192139.

It is an arithmetic number, because the mean of its divisors is an integer number (117576405).

Almost surely, 2^391921345 is an apocalyptic number.

It is an amenable number.

391921345 is a deficient number, since it is larger than the sum of its proper divisors (78384275).

391921345 is an equidigital number, since it uses as much as digits as its factorization.

391921345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78384274.

The product of its digits is 29160, while the sum is 37.

The square root of 391921345 is about 19797.0034348636. The cubic root of 391921345 is about 731.8121892931.

The spelling of 391921345 in words is "three hundred ninety-one million, nine hundred twenty-one thousand, three hundred forty-five".