21253823 has 8 divisors (see below), whose sum is σ = 21954240. Its totient is φ = 20563840.

The previous prime is 21253763. The next prime is 21253849. The reversal of 21253823 is 32835212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21253823 - 2⁶ = 21253759 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21253792 and 21253801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21253853) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1643 + ... + 6723.

It is an arithmetic number, because the mean of its divisors is an integer number (2744280).

Almost surely, 2^21253823 is an apocalyptic number.

21253823 is a deficient number, since it is larger than the sum of its proper divisors (700417).

21253823 is an equidigital number, since it uses as much as digits as its factorization.

21253823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5217.

The product of its digits is 2880, while the sum is 26.

The square root of 21253823 is about 4610.1868725682. The cubic root of 21253823 is about 276.9995221268. Note that the first 3 decimals are identical.

The spelling of 21253823 in words is "twenty-one million, two hundred fifty-three thousand, eight hundred twenty-three".