21916361 has 4 divisors (see below), whose sum is σ = 21975492. Its totient is φ = 21857232.

The previous prime is 21916357. The next prime is 21916379. The reversal of 21916361 is 16361912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17272336 + 4644025 = 4156^2 + 2155^2 .

It is a cyclic number.

It is not a de Polignac number, because 21916361 - 2² = 21916357 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21916331) 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, 29006 + ... + 29751.

It is an arithmetic number, because the mean of its divisors is an integer number (5493873).

Almost surely, 2^21916361 is an apocalyptic number.

It is an amenable number.

21916361 is a deficient number, since it is larger than the sum of its proper divisors (59131).

21916361 is an equidigital number, since it uses as much as digits as its factorization.

21916361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59130.

The product of its digits is 1944, while the sum is 29.

The square root of 21916361 is about 4681.4913222177. The cubic root of 21916361 is about 279.8483915646.

The spelling of 21916361 in words is "twenty-one million, nine hundred sixteen thousand, three hundred sixty-one".