21968611 has 24 divisors (see below), whose sum is σ = 27069984. Its totient is φ = 17740800.

The previous prime is 21968603. The next prime is 21968633. The reversal of 21968611 is 11686912.

It is not a de Polignac number, because 21968611 - 2³ = 21968603 is a prime.

It is a Smith number, since the sum of its digits (34) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

Its product of digits (5184) is a multiple of the sum of its prime divisors (324).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21968711) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 113731 + ... + 113923.

It is an arithmetic number, because the mean of its divisors is an integer number (1127916).

Almost surely, 2^21968611 is an apocalyptic number.

21968611 is a deficient number, since it is larger than the sum of its proper divisors (5101373).

21968611 is a wasteful number, since it uses less digits than its factorization.

21968611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331 (or 324 counting only the distinct ones).

The product of its digits is 5184, while the sum is 34.

The square root of 21968611 is about 4687.0684868049. The cubic root of 21968611 is about 280.0706071936.

The spelling of 21968611 in words is "twenty-one million, nine hundred sixty-eight thousand, six hundred eleven".