21965791 has 4 divisors (see below), whose sum is σ = 22501584. Its totient is φ = 21430000.

The previous prime is 21965771. The next prime is 21965807. The reversal of 21965791 is 19756912.

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 21965791 - 2¹¹ = 21963743 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 (21965761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 267835 + ... + 267916.

It is an arithmetic number, because the mean of its divisors is an integer number (5625396).

Almost surely, 2^21965791 is an apocalyptic number.

21965791 is a deficient number, since it is larger than the sum of its proper divisors (535793).

21965791 is an equidigital number, since it uses as much as digits as its factorization.

21965791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535792.

The product of its digits is 34020, while the sum is 40.

The square root of 21965791 is about 4686.7676494574. The cubic root of 21965791 is about 280.0586229295.

The spelling of 21965791 in words is "twenty-one million, nine hundred sixty-five thousand, seven hundred ninety-one".