391421 has 4 divisors (see below), whose sum is σ = 392700. Its totient is φ = 390144.

The previous prime is 391403. The next prime is 391441. The reversal of 391421 is 124193.

391421 is nontrivially palindromic in base 2.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 240100 + 151321 = 490^2 + 389^2 .

It is a cyclic number.

It is not a de Polignac number, because 391421 - 2¹⁸ = 129277 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 391393 and 391402.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 391421.

It is not an unprimeable number, because it can be changed into a prime (391441) 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, 125 + ... + 893.

It is an arithmetic number, because the mean of its divisors is an integer number (98175).

2³⁹¹⁴²¹ is an apocalyptic number.

It is an amenable number.

391421 is a deficient number, since it is larger than the sum of its proper divisors (1279).

391421 is an equidigital number, since it uses as much as digits as its factorization.

391421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1278.

The product of its digits is 216, while the sum is 20.

The square root of 391421 is about 625.6364759187. The cubic root of 391421 is about 73.1500634859.

The spelling of 391421 in words is "three hundred ninety-one thousand, four hundred twenty-one".