21404024 has 24 divisors (see below), whose sum is σ = 41115960. Its totient is φ = 10445904.

The previous prime is 21404017. The next prime is 21404029. The reversal of 21404024 is 42040412.

It is a junction number, because it is equal to n+sod(n) for n = 21403993 and 21404011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404029) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14069 + ... + 15515.

It is an arithmetic number, because the mean of its divisors is an integer number (1713165).

Almost surely, 2^21404024 is an apocalyptic number.

It is an amenable number.

21404024 is a deficient number, since it is larger than the sum of its proper divisors (19711936).

21404024 is a wasteful number, since it uses less digits than its factorization.

21404024 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1539 (or 1492 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21404024 is about 4626.4483137716. The cubic root of 21404024 is about 277.6505105651.

Adding to 21404024 its reverse (42040412), we get a palindrome (63444436).

The spelling of 21404024 in words is "twenty-one million, four hundred four thousand, twenty-four".