391311421 has 4 divisors (see below), whose sum is σ = 400855644. Its totient is φ = 381767200.

The previous prime is 391311407. The next prime is 391311433. The reversal of 391311421 is 124113193.

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

It can be written as a sum of positive squares in 2 ways, for example, as 67815225 + 323496196 = 8235^2 + 17986^2 .

It is a cyclic number.

It is not a de Polignac number, because 391311421 - 2⁷ = 391311293 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (391311451) 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, 4772050 + ... + 4772131.

It is an arithmetic number, because the mean of its divisors is an integer number (100213911).

Almost surely, 2^391311421 is an apocalyptic number.

It is an amenable number.

391311421 is a deficient number, since it is larger than the sum of its proper divisors (9544223).

391311421 is an equidigital number, since it uses as much as digits as its factorization.

391311421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9544222.

The product of its digits is 648, while the sum is 25.

The square root of 391311421 is about 19781.5929843883. The cubic root of 391311421 is about 731.4323668565.

The spelling of 391311421 in words is "three hundred ninety-one million, three hundred eleven thousand, four hundred twenty-one".