21242633 has 4 divisors (see below), whose sum is σ = 21760788. Its totient is φ = 20724480.

The previous prime is 21242629. The next prime is 21242651. The reversal of 21242633 is 33624212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 1776889 + 19465744 = 1333^2 + 4412^2 .

It is a cyclic number.

It is not a de Polignac number, because 21242633 - 2² = 21242629 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21242599 and 21242608.

It is not an unprimeable number, because it can be changed into a prime (21242833) 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, 259016 + ... + 259097.

It is an arithmetic number, because the mean of its divisors is an integer number (5440197).

Almost surely, 2^21242633 is an apocalyptic number.

It is an amenable number.

21242633 is a deficient number, since it is larger than the sum of its proper divisors (518155).

21242633 is an equidigital number, since it uses as much as digits as its factorization.

21242633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518154.

The product of its digits is 1728, while the sum is 23.

The square root of 21242633 is about 4608.9730960378. The cubic root of 21242633 is about 276.9509007755.

Adding to 21242633 its reverse (33624212), we get a palindrome (54866845).

The spelling of 21242633 in words is "twenty-one million, two hundred forty-two thousand, six hundred thirty-three".