21922 has 8 divisors (see below), whose sum is σ = 33516. Its totient is φ = 10752.

The previous prime is 21911. The next prime is 21929. The reversal of 21922 is 22912.

It is a happy number.

21922 is an esthetic number in base 15, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in 2 ways, for example, as 19321 + 2601 = 139^2 + 51^2 .

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

21922 is an undulating number in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 21896 and 21905.

It is not an unprimeable number, because it can be changed into a prime (21929) by changing a digit.

21922 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138 + ... + 250.

2²¹⁹²² is an apocalyptic number.

21922 is a deficient number, since it is larger than the sum of its proper divisors (11594).

21922 is a wasteful number, since it uses less digits than its factorization.

21922 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212.

The product of its digits is 72, while the sum is 16.

The square root of 21922 is about 148.0607983229. The cubic root of 21922 is about 27.9872390831.

Subtracting 21922 from its reverse (22912), we obtain a triangular number (990 = T₄₄).

It can be divided in two parts, 2 and 1922, that multiplied together give a square (3844 = 62²).

The spelling of 21922 in words is "twenty-one thousand, nine hundred twenty-two".