406921 has 4 divisors (see below), whose sum is σ = 410832. Its totient is φ = 403012.

The previous prime is 406907. The next prime is 406951. The reversal of 406921 is 129604.

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 406921 - 2¹³ = 398729 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 406892 and 406901.

It is not an unprimeable number, because it can be changed into a prime (406951) 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, 1795 + ... + 2008.

It is an arithmetic number, because the mean of its divisors is an integer number (102708).

2⁴⁰⁶⁹²¹ is an apocalyptic number.

It is an amenable number.

406921 is a deficient number, since it is larger than the sum of its proper divisors (3911).

406921 is a wasteful number, since it uses less digits than its factorization.

406921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3910.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 406921 is about 637.9035977324. The cubic root of 406921 is about 74.1031553806.

The spelling of 406921 in words is "four hundred six thousand, nine hundred twenty-one".