21965911 has 4 divisors (see below), whose sum is σ = 23962824. Its totient is φ = 19969000.

The previous prime is 21965899. The next prime is 21965927. The reversal of 21965911 is 11956912.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21965911 - 2¹¹ = 21963863 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21965971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 998440 + ... + 998461.

It is an arithmetic number, because the mean of its divisors is an integer number (5990706).

Almost surely, 2^21965911 is an apocalyptic number.

21965911 is a deficient number, since it is larger than the sum of its proper divisors (1996913).

21965911 is a wasteful number, since it uses less digits than its factorization.

21965911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1996912.

The product of its digits is 4860, while the sum is 34.

The square root of 21965911 is about 4686.7804514400. The cubic root of 21965911 is about 280.0591329191.

The spelling of 21965911 in words is "twenty-one million, nine hundred sixty-five thousand, nine hundred eleven".