21640233 has 8 divisors (see below), whose sum is σ = 29219200. Its totient is φ = 14244048.

The previous prime is 21640231. The next prime is 21640237. The reversal of 21640233 is 33204612.

It is a happy number.

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

It is not a de Polignac number, because 21640233 - 2¹ = 21640231 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21640231) 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, 45418 + ... + 45891.

It is an arithmetic number, because the mean of its divisors is an integer number (3652400).

Almost surely, 2^21640233 is an apocalyptic number.

It is an amenable number.

21640233 is a deficient number, since it is larger than the sum of its proper divisors (7578967).

21640233 is an equidigital number, since it uses as much as digits as its factorization.

21640233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91391.

The product of its (nonzero) digits is 864, while the sum is 21.

The square root of 21640233 is about 4651.9063834088. The cubic root of 21640233 is about 278.6681348475.

Adding to 21640233 its reverse (33204612), we get a palindrome (54844845).

The spelling of 21640233 in words is "twenty-one million, six hundred forty thousand, two hundred thirty-three".