420344021 has 4 divisors (see below), whose sum is σ = 438619872. Its totient is φ = 402068172.

The previous prime is 420344017. The next prime is 420344039. The reversal of 420344021 is 120443024.

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 a cyclic number.

It is not a de Polignac number, because 420344021 - 2² = 420344017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 420343984 and 420344002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (420344321) 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, 9137891 + ... + 9137936.

It is an arithmetic number, because the mean of its divisors is an integer number (109654968).

Almost surely, 2^420344021 is an apocalyptic number.

It is an amenable number.

420344021 is a deficient number, since it is larger than the sum of its proper divisors (18275851).

420344021 is a wasteful number, since it uses less digits than its factorization.

420344021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18275850.

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 420344021 is about 20502.2930668743. The cubic root of 420344021 is about 749.0916535048.

Adding to 420344021 its reverse (120443024), we get a palindrome (540787045).

The spelling of 420344021 in words is "four hundred twenty million, three hundred forty-four thousand, twenty-one".