21855706 has 16 divisors (see below), whose sum is σ = 33781608. Its totient is φ = 10598400.

The previous prime is 21855697. The next prime is 21855709. The reversal of 21855706 is 60755812.

It can be written as a sum of positive squares in 4 ways, for example, as 9891025 + 11964681 = 3145^2 + 3459^2 .

It is not an unprimeable number, because it can be changed into a prime (21855709) 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, 15136 + ... + 16516.

Almost surely, 2^21855706 is an apocalyptic number.

21855706 is a deficient number, since it is larger than the sum of its proper divisors (11925902).

21855706 is a wasteful number, since it uses less digits than its factorization.

21855706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1617.

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 21855706 is about 4675.0086630936. The cubic root of 21855706 is about 279.5899866315.

The spelling of 21855706 in words is "twenty-one million, eight hundred fifty-five thousand, seven hundred six".