21143923 has 4 divisors (see below), whose sum is σ = 22063248. Its totient is φ = 20224600.

The previous prime is 21143921. The next prime is 21143951. The reversal of 21143923 is 32934112.

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

It is a cyclic number.

It is not a de Polignac number, because 21143923 - 2¹ = 21143921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21143921) 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, 459628 + ... + 459673.

It is an arithmetic number, because the mean of its divisors is an integer number (5515812).

Almost surely, 2^21143923 is an apocalyptic number.

21143923 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21143923 is a deficient number, since it is larger than the sum of its proper divisors (919325).

21143923 is an equidigital number, since it uses as much as digits as its factorization.

21143923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 919324.

The product of its digits is 1296, while the sum is 25.

The square root of 21143923 is about 4598.2521679438. The cubic root of 21143923 is about 276.5212572779.

The spelling of 21143923 in words is "twenty-one million, one hundred forty-three thousand, nine hundred twenty-three".