21404033 has 12 divisors (see below), whose sum is σ = 25039872. Its totient is φ = 18242280.

The previous prime is 21404029. The next prime is 21404063. The reversal of 21404033 is 33040412.

It is not a de Polignac number, because 21404033 - 2² = 21404029 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21404063) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8216 + ... + 10502.

It is an arithmetic number, because the mean of its divisors is an integer number (2086656).

Almost surely, 2^21404033 is an apocalyptic number.

It is an amenable number.

21404033 is a deficient number, since it is larger than the sum of its proper divisors (3635839).

21404033 is a wasteful number, since it uses less digits than its factorization.

21404033 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2492 (or 2485 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21404033 is about 4626.4492864399. The cubic root of 21404033 is about 277.6505494807.

Adding to 21404033 its reverse (33040412), we get a palindrome (54444445).

The spelling of 21404033 in words is "twenty-one million, four hundred four thousand, thirty-three".