21966361 has 4 divisors (see below), whose sum is σ = 21976272. Its totient is φ = 21956452.

The previous prime is 21966359. The next prime is 21966401. The reversal of 21966361 is 16366912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21966361 - 2¹ = 21966359 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21966331) 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 3 ways as a sum of consecutive naturals, for example, 66 + ... + 6628.

It is an arithmetic number, because the mean of its divisors is an integer number (5494068).

Almost surely, 2^21966361 is an apocalyptic number.

It is an amenable number.

21966361 is a deficient number, since it is larger than the sum of its proper divisors (9911).

21966361 is an equidigital number, since it uses as much as digits as its factorization.

21966361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9910.

The product of its digits is 11664, while the sum is 34.

The square root of 21966361 is about 4686.8284585634. The cubic root of 21966361 is about 280.0610453634.

The spelling of 21966361 in words is "twenty-one million, nine hundred sixty-six thousand, three hundred sixty-one".