21919441 has 2 divisors, whose sum is σ = 21919442. Its totient is φ = 21919440.

The previous prime is 21919439. The next prime is 21919459. The reversal of 21919441 is 14491912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15523600 + 6395841 = 3940^2 + 2529^2 .

It is a cyclic number.

It is not a de Polignac number, because 21919441 - 2¹ = 21919439 is a prime.

Together with 21919439, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21919411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10959720 + 10959721.

It is an arithmetic number, because the mean of its divisors is an integer number (10959721).

Almost surely, 2^21919441 is an apocalyptic number.

It is an amenable number.

21919441 is a deficient number, since it is larger than the sum of its proper divisors (1).

21919441 is an equidigital number, since it uses as much as digits as its factorization.

21919441 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 31.

The square root of 21919441 is about 4681.8202656659. The cubic root of 21919441 is about 279.8615003812.

The spelling of 21919441 in words is "twenty-one million, nine hundred nineteen thousand, four hundred forty-one".