21965539 has 8 divisors (see below), whose sum is σ = 23306240. Its totient is φ = 20643336.

The previous prime is 21965527. The next prime is 21965563. The reversal of 21965539 is 93556912.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21965539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21965519) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2139 + ... + 6964.

It is an arithmetic number, because the mean of its divisors is an integer number (2913280).

Almost surely, 2^21965539 is an apocalyptic number.

21965539 is a deficient number, since it is larger than the sum of its proper divisors (1340701).

21965539 is a wasteful number, since it uses less digits than its factorization.

21965539 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9249.

The product of its digits is 72900, while the sum is 40.

The square root of 21965539 is about 4686.7407651800. The cubic root of 21965539 is about 280.0575519453.

The spelling of 21965539 in words is "twenty-one million, nine hundred sixty-five thousand, five hundred thirty-nine".