21131404 has 24 divisors (see below), whose sum is σ = 43248128. Its totient is φ = 8845200.

The previous prime is 21131399. The next prime is 21131419. The reversal of 21131404 is 40413112.

It is a super-2 number, since 2×21131404² = 893072470022432, which contains 22 as substring.

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, 7572 + ... + 9979.

Almost surely, 2^21131404 is an apocalyptic number.

It is an amenable number.

21131404 is an abundant number, since it is smaller than the sum of its proper divisors (22116724).

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

21131404 is a wasteful number, since it uses less digits than its factorization.

21131404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17605 (or 17603 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21131404 is about 4596.8906882805. The cubic root of 21131404 is about 276.4666718056.

Adding to 21131404 its reverse (40413112), we get a palindrome (61544516).

The spelling of 21131404 in words is "twenty-one million, one hundred thirty-one thousand, four hundred four".