21814021 has 2 divisors, whose sum is σ = 21814022. Its totient is φ = 21814020.

The previous prime is 21813997. The next prime is 21814069. The reversal of 21814021 is 12041812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14333796 + 7480225 = 3786^2 + 2735^2 .

It is a cyclic number.

It is not a de Polignac number, because 21814021 - 2¹³ = 21805829 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21814021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21814321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10907010 + 10907011.

It is an arithmetic number, because the mean of its divisors is an integer number (10907011).

Almost surely, 2^21814021 is an apocalyptic number.

It is an amenable number.

21814021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21814021 is an equidigital number, since it uses as much as digits as its factorization.

21814021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21814021 is about 4670.5482547555. The cubic root of 21814021 is about 279.4121211645.

Adding to 21814021 its reverse (12041812), we get a palindrome (33855833).

The spelling of 21814021 in words is "twenty-one million, eight hundred fourteen thousand, twenty-one".