21231404 has 24 divisors (see below), whose sum is σ = 39180288. Its totient is φ = 10051920.

The previous prime is 21231403. The next prime is 21231407. The reversal of 21231404 is 40413212.

It is a super-2 number, since 2×21231404² = 901545031622432, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21231403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4007 + ... + 7649.

It is an arithmetic number, because the mean of its divisors is an integer number (1632512).

Almost surely, 2^21231404 is an apocalyptic number.

It is an amenable number.

21231404 is a deficient number, since it is larger than the sum of its proper divisors (17948884).

21231404 is a wasteful number, since it uses less digits than its factorization.

21231404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3725 (or 3723 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21231404 is about 4607.7547677801. The cubic root of 21231404 is about 276.9020927990.

Adding to 21231404 its reverse (40413212), we get a palindrome (61644616).

The spelling of 21231404 in words is "twenty-one million, two hundred thirty-one thousand, four hundred four".