21023853 has 4 divisors (see below), whose sum is σ = 28031808. Its totient is φ = 14015900.

The previous prime is 21023851. The next prime is 21023867. The reversal of 21023853 is 35832012.

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 21023853 - 2¹ = 21023851 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21023851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3503973 + ... + 3503978.

It is an arithmetic number, because the mean of its divisors is an integer number (7007952).

Almost surely, 2^21023853 is an apocalyptic number.

It is an amenable number.

21023853 is a deficient number, since it is larger than the sum of its proper divisors (7007955).

21023853 is an equidigital number, since it uses as much as digits as its factorization.

21023853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7007954.

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21023853 is about 4585.1775320046. The cubic root of 21023853 is about 275.9968362376.

Adding to 21023853 its reverse (35832012), we get a palindrome (56855865).

The spelling of 21023853 in words is "twenty-one million, twenty-three thousand, eight hundred fifty-three".