21240233 has 8 divisors (see below), whose sum is σ = 25552320. Its totient is φ = 17247600.

The previous prime is 21240223. The next prime is 21240251. The reversal of 21240233 is 33204212.

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 21240233 - 2¹⁴ = 21223849 is a prime.

It is a super-2 number, since 2×21240233² = 902294995788578, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21240223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79718 + ... + 79983.

It is an arithmetic number, because the mean of its divisors is an integer number (3194040).

Almost surely, 2^21240233 is an apocalyptic number.

It is an amenable number.

21240233 is a deficient number, since it is larger than the sum of its proper divisors (4312087).

21240233 is a wasteful number, since it uses less digits than its factorization.

21240233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159727.

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

The square root of 21240233 is about 4608.7127269987. The cubic root of 21240233 is about 276.9404703799.

Adding to 21240233 its reverse (33204212), we get a palindrome (54444445).

The spelling of 21240233 in words is "twenty-one million, two hundred forty thousand, two hundred thirty-three".