404389721 has 4 divisors (see below), whose sum is σ = 404700432. Its totient is φ = 404079012.

The previous prime is 404389709. The next prime is 404389751. The reversal of 404389721 is 127983404.

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 404389721 - 2²⁶ = 337280857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (404389751) 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, 153395 + ... + 156008.

It is an arithmetic number, because the mean of its divisors is an integer number (101175108).

Almost surely, 2^404389721 is an apocalyptic number.

It is an amenable number.

404389721 is a deficient number, since it is larger than the sum of its proper divisors (310711).

404389721 is a wasteful number, since it uses less digits than its factorization.

404389721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 310710.

The product of its (nonzero) digits is 48384, while the sum is 38.

The square root of 404389721 is about 20109.4435775831. The cubic root of 404389721 is about 739.4918114218.

The spelling of 404389721 in words is "four hundred four million, three hundred eighty-nine thousand, seven hundred twenty-one".