404431220 has 24 divisors (see below), whose sum is σ = 863231208. Its totient is φ = 159120000.

The previous prime is 404431189. The next prime is 404431243. The reversal of 404431220 is 22134404.

404431220 = 1776² + 1777² + ... + 1895².

It can be written as a sum of positive squares in 4 ways, for example, as 43507216 + 360924004 = 6596^2 + 18998^2 .

It is a super-2 number, since 2×404431220² = 327129223421376800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 404431192 and 404431201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164531 + ... + 166970.

It is an arithmetic number, because the mean of its divisors is an integer number (35967967).

Almost surely, 2^404431220 is an apocalyptic number.

It is an amenable number.

404431220 is an abundant number, since it is smaller than the sum of its proper divisors (458799988).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

404431220 is a wasteful number, since it uses less digits than its factorization.

404431220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331571 (or 331569 counting only the distinct ones).

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

The square root of 404431220 is about 20110.4753797617. The cubic root of 404431220 is about 739.5171064276.

Adding to 404431220 its reverse (22134404), we get a palindrome (426565624).

The spelling of 404431220 in words is "four hundred four million, four hundred thirty-one thousand, two hundred twenty".