21889643 has 2 divisors, whose sum is σ = 21889644. Its totient is φ = 21889642.

The previous prime is 21889601. The next prime is 21889657. The reversal of 21889643 is 34698812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21889643 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21889643.

It is not a weakly prime, because it can be changed into another prime (21889943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10944821 + 10944822.

It is an arithmetic number, because the mean of its divisors is an integer number (10944822).

Almost surely, 2^21889643 is an apocalyptic number.

21889643 is a deficient number, since it is larger than the sum of its proper divisors (1).

21889643 is an equidigital number, since it uses as much as digits as its factorization.

21889643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 41.

The square root of 21889643 is about 4678.6368741333. The cubic root of 21889643 is about 279.7346252667.

The spelling of 21889643 in words is "twenty-one million, eight hundred eighty-nine thousand, six hundred forty-three".