21944421 has 12 divisors (see below), whose sum is σ = 31860972. Its totient is φ = 14554176.

The previous prime is 21944413. The next prime is 21944423. The reversal of 21944421 is 12444912.

It is a happy number.

21944421 is a `hidden beast` number, since 219 + 4 + 442 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 13176900 + 8767521 = 3630^2 + 2961^2 .

It is not a de Polignac number, because 21944421 - 2³ = 21944413 is a prime.

It is a super-2 number, since 2×21944421² = 963115226050482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21944423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4416 + ... + 7961.

It is an arithmetic number, because the mean of its divisors is an integer number (2655081).

Almost surely, 2^21944421 is an apocalyptic number.

It is an amenable number.

21944421 is a deficient number, since it is larger than the sum of its proper divisors (9916551).

21944421 is a wasteful number, since it uses less digits than its factorization.

21944421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12580 (or 12577 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21944421 is about 4684.4872718367. The cubic root of 21944421 is about 279.9677726514.

The spelling of 21944421 in words is "twenty-one million, nine hundred forty-four thousand, four hundred twenty-one".