21956747 has 4 divisors (see below), whose sum is σ = 21966120. Its totient is φ = 21947376.

The previous prime is 21956731. The next prime is 21956777. The reversal of 21956747 is 74765912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21956747 - 2⁴ = 21956731 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21956717) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2279 + ... + 7007.

It is an arithmetic number, because the mean of its divisors is an integer number (5491530).

Almost surely, 2^21956747 is an apocalyptic number.

21956747 is a deficient number, since it is larger than the sum of its proper divisors (9373).

21956747 is an equidigital number, since it uses as much as digits as its factorization.

21956747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9372.

The product of its digits is 105840, while the sum is 41.

The square root of 21956747 is about 4685.8027060473. The cubic root of 21956747 is about 280.0201813685.

The spelling of 21956747 in words is "twenty-one million, nine hundred fifty-six thousand, seven hundred forty-seven".