21002243 has 8 divisors (see below), whose sum is σ = 22134816. Its totient is φ = 19888000.

The previous prime is 21002231. The next prime is 21002251. The reversal of 21002243 is 34220012.

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 21002243 - 2¹⁸ = 20740099 is a prime.

It is a super-2 number, since 2×21002243² = 882188422062098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002203) 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, 2198 + ... + 6843.

It is an arithmetic number, because the mean of its divisors is an integer number (2766852).

Almost surely, 2^21002243 is an apocalyptic number.

21002243 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21002243 is a deficient number, since it is larger than the sum of its proper divisors (1132573).

21002243 is a wasteful number, since it uses less digits than its factorization.

21002243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9165.

The product of its (nonzero) digits is 96, while the sum is 14.

The square root of 21002243 is about 4582.8204197852. The cubic root of 21002243 is about 275.9022399343.

Adding to 21002243 its reverse (34220012), we get a palindrome (55222255).

The spelling of 21002243 in words is "twenty-one million, two thousand, two hundred forty-three".