21722843 has 4 divisors (see below), whose sum is σ = 21984648. Its totient is φ = 21461040.

The previous prime is 21722837. The next prime is 21722851. The reversal of 21722843 is 34822712.

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 21722843 - 2⁸ = 21722587 is a prime.

It is a super-3 number, since 3×21722843³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21722863) 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, 130778 + ... + 130943.

It is an arithmetic number, because the mean of its divisors is an integer number (5496162).

Almost surely, 2^21722843 is an apocalyptic number.

21722843 is a deficient number, since it is larger than the sum of its proper divisors (261805).

21722843 is an equidigital number, since it uses as much as digits as its factorization.

21722843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261804.

The product of its digits is 5376, while the sum is 29.

The square root of 21722843 is about 4660.7770811314. Note that the first 3 decimals coincide. The cubic root of 21722843 is about 279.0222829631.

The spelling of 21722843 in words is "twenty-one million, seven hundred twenty-two thousand, eight hundred forty-three".