21800023 has 4 divisors (see below), whose sum is σ = 24914320. Its totient is φ = 18685728.

The previous prime is 21800017. The next prime is 21800039. The reversal of 21800023 is 32000812.

It is a happy number.

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 21800023 - 2²¹ = 19702871 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 (21800003) 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, 1557138 + ... + 1557151.

It is an arithmetic number, because the mean of its divisors is an integer number (6228580).

Almost surely, 2^21800023 is an apocalyptic number.

21800023 is a deficient number, since it is larger than the sum of its proper divisors (3114297).

21800023 is an equidigital number, since it uses as much as digits as its factorization.

21800023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3114296.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21800023 is about 4669.0494750002. The cubic root of 21800023 is about 279.3523423679.

Adding to 21800023 its reverse (32000812), we get a palindrome (53800835).

The spelling of 21800023 in words is "twenty-one million, eight hundred thousand, twenty-three".