21956829 has 4 divisors (see below), whose sum is σ = 29275776. Its totient is φ = 14637884.

The previous prime is 21956827. The next prime is 21956839. The reversal of 21956829 is 92865912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21956829 - 2¹ = 21956827 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21956827) 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, 3659469 + ... + 3659474.

It is an arithmetic number, because the mean of its divisors is an integer number (7318944).

Almost surely, 2^21956829 is an apocalyptic number.

It is an amenable number.

21956829 is a deficient number, since it is larger than the sum of its proper divisors (7318947).

21956829 is an equidigital number, since it uses as much as digits as its factorization.

21956829 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7318946.

The product of its digits is 77760, while the sum is 42.

The square root of 21956829 is about 4685.8114558740. The cubic root of 21956829 is about 280.0205299573.

The spelling of 21956829 in words is "twenty-one million, nine hundred fifty-six thousand, eight hundred twenty-nine".