21855707 has 4 divisors (see below), whose sum is σ = 21866280. Its totient is φ = 21845136.

The previous prime is 21855697. The next prime is 21855709. The reversal of 21855707 is 70755812.

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 a de Polignac number, because none of the positive numbers 2^k-21855707 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21855709) 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, 1058 + ... + 6695.

It is an arithmetic number, because the mean of its divisors is an integer number (5466570).

Almost surely, 2^21855707 is an apocalyptic number.

21855707 is a deficient number, since it is larger than the sum of its proper divisors (10573).

21855707 is an equidigital number, since it uses as much as digits as its factorization.

21855707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10572.

The product of its (nonzero) digits is 19600, while the sum is 35.

The square root of 21855707 is about 4675.0087700452. The cubic root of 21855707 is about 279.5899908956.

The spelling of 21855707 in words is "twenty-one million, eight hundred fifty-five thousand, seven hundred seven".