21854021 has 4 divisors (see below), whose sum is σ = 24976032. Its totient is φ = 18732012.

The previous prime is 21854011. The next prime is 21854051. The reversal of 21854021 is 12045812.

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 21854021 - 2¹⁰ = 21852997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21854011) 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, 1560995 + ... + 1561008.

It is an arithmetic number, because the mean of its divisors is an integer number (6244008).

Almost surely, 2^21854021 is an apocalyptic number.

It is an amenable number.

21854021 is a deficient number, since it is larger than the sum of its proper divisors (3122011).

21854021 is an equidigital number, since it uses as much as digits as its factorization.

21854021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3122010.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21854021 is about 4674.8284460502. The cubic root of 21854021 is about 279.5828013037.

Adding to 21854021 its reverse (12045812), we get a palindrome (33899833).

The spelling of 21854021 in words is "twenty-one million, eight hundred fifty-four thousand, twenty-one".