21864235 has 4 divisors (see below), whose sum is σ = 26237088. Its totient is φ = 17491384.

The previous prime is 21864229. The next prime is 21864239. The reversal of 21864235 is 53246812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21864235 - 2⁷ = 21864107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21864197 and 21864206.

It is not an unprimeable number, because it can be changed into a prime (21864239) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2186419 + ... + 2186428.

It is an arithmetic number, because the mean of its divisors is an integer number (6559272).

Almost surely, 2^21864235 is an apocalyptic number.

21864235 is a deficient number, since it is larger than the sum of its proper divisors (4372853).

21864235 is an equidigital number, since it uses as much as digits as its factorization.

21864235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4372852.

The product of its digits is 11520, while the sum is 31.

The square root of 21864235 is about 4675.9207649403. The cubic root of 21864235 is about 279.6263510919.

The spelling of 21864235 in words is "twenty-one million, eight hundred sixty-four thousand, two hundred thirty-five".