21513233 has 8 divisors (see below), whose sum is σ = 25186560. Its totient is φ = 17989920.

The previous prime is 21513227. The next prime is 21513241. The reversal of 21513233 is 33231512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21513233 - 2¹⁶ = 21447697 is a prime.

It is a super-2 number, since 2×21513233² = 925638388224578, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21513203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37193 + ... + 37766.

It is an arithmetic number, because the mean of its divisors is an integer number (3148320).

Almost surely, 2^21513233 is an apocalyptic number.

It is an amenable number.

21513233 is a deficient number, since it is larger than the sum of its proper divisors (3673327).

21513233 is an equidigital number, since it uses as much as digits as its factorization.

21513233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75007.

The product of its digits is 540, while the sum is 20.

The square root of 21513233 is about 4638.2359793352. The cubic root of 21513233 is about 278.1219251943.

Adding to 21513233 its reverse (33231512), we get a palindrome (54744745).

The spelling of 21513233 in words is "twenty-one million, five hundred thirteen thousand, two hundred thirty-three".