21164023 has 4 divisors (see below), whose sum is σ = 21174048. Its totient is φ = 21154000.

The previous prime is 21163999. The next prime is 21164029. The reversal of 21164023 is 32046112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21164023 - 2⁵ = 21163991 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 (21164029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 478 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (5293512).

Almost surely, 2^21164023 is an apocalyptic number.

21164023 is a deficient number, since it is larger than the sum of its proper divisors (10025).

21164023 is an equidigital number, since it uses as much as digits as its factorization.

21164023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10024.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21164023 is about 4600.4372618263. The cubic root of 21164023 is about 276.6088524540.

The spelling of 21164023 in words is "twenty-one million, one hundred sixty-four thousand, twenty-three".