408721 has 4 divisors (see below), whose sum is σ = 412452. Its totient is φ = 404992.

The previous prime is 408719. The next prime is 408743. The reversal of 408721 is 127804.

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 4225 + 404496 = 65^2 + 636^2 .

It is not a de Polignac number, because 408721 - 2¹ = 408719 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 an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 408692 and 408701.

It is not an unprimeable number, because it can be changed into a prime (408701) 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, 1696 + ... + 1921.

It is an arithmetic number, because the mean of its divisors is an integer number (103113).

2⁴⁰⁸⁷²¹ is an apocalyptic number.

It is an amenable number.

408721 is a deficient number, since it is larger than the sum of its proper divisors (3731).

408721 is a wasteful number, since it uses less digits than its factorization.

408721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3730.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 408721 is about 639.3129124302. The cubic root of 408721 is about 74.2122588561.

The spelling of 408721 in words is "four hundred eight thousand, seven hundred twenty-one".