21966289 has 2 divisors, whose sum is σ = 21966290. Its totient is φ = 21966288.

The previous prime is 21966281. The next prime is 21966293. The reversal of 21966289 is 98266912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19210689 + 2755600 = 4383^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 21966289 - 2³ = 21966281 is a prime.

It is not a weakly prime, because it can be changed into another prime (21966281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10983144 + 10983145.

It is an arithmetic number, because the mean of its divisors is an integer number (10983145).

Almost surely, 2^21966289 is an apocalyptic number.

It is an amenable number.

21966289 is a deficient number, since it is larger than the sum of its proper divisors (1).

21966289 is an equidigital number, since it uses as much as digits as its factorization.

21966289 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 43.

The square root of 21966289 is about 4686.8207774567. The cubic root of 21966289 is about 280.0607393741.

The spelling of 21966289 in words is "twenty-one million, nine hundred sixty-six thousand, two hundred eighty-nine".