21684633 has 4 divisors (see below), whose sum is σ = 28912848. Its totient is φ = 14456420.

The previous prime is 21684623. The next prime is 21684647. The reversal of 21684633 is 33648612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21684633 - 2²¹ = 19587481 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21684594 and 21684603.

It is not an unprimeable number, because it can be changed into a prime (21684623) 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, 3614103 + ... + 3614108.

It is an arithmetic number, because the mean of its divisors is an integer number (7228212).

Almost surely, 2^21684633 is an apocalyptic number.

It is an amenable number.

21684633 is a deficient number, since it is larger than the sum of its proper divisors (7228215).

21684633 is an equidigital number, since it uses as much as digits as its factorization.

21684633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7228214.

The product of its digits is 20736, while the sum is 33.

The square root of 21684633 is about 4656.6761751275. The cubic root of 21684633 is about 278.8585889410.

The spelling of 21684633 in words is "twenty-one million, six hundred eighty-four thousand, six hundred thirty-three".