21551033 has 16 divisors (see below), whose sum is σ = 25468800. Its totient is φ = 18225648.

The previous prime is 21550939. The next prime is 21551039. The reversal of 21551033 is 33015512.

It is not a de Polignac number, because 21551033 - 2⁸ = 21550777 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21550996 and 21551014.

It is not an unprimeable number, because it can be changed into a prime (21551039) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28091 + ... + 28847.

It is an arithmetic number, because the mean of its divisors is an integer number (1591800).

Almost surely, 2^21551033 is an apocalyptic number.

It is an amenable number.

21551033 is a deficient number, since it is larger than the sum of its proper divisors (3917767).

21551033 is an frugal number, since it uses more digits than its factorization.

21551033 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 861 (or 847 counting only the distinct ones).

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21551033 is about 4642.3090159962. The cubic root of 21551033 is about 278.2847220095.

Adding to 21551033 its reverse (33015512), we get a palindrome (54566545).

The spelling of 21551033 in words is "twenty-one million, five hundred fifty-one thousand, thirty-three".