21856122 has 32 divisors (see below), whose sum is σ = 49886400. Its totient is φ = 7087824.

The previous prime is 21856069. The next prime is 21856129. The reversal of 21856122 is 22165812.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21856129) 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 15 ways as a sum of consecutive naturals, for example, 3472 + ... + 7467.

It is an arithmetic number, because the mean of its divisors is an integer number (1558950).

Almost surely, 2^21856122 is an apocalyptic number.

21856122 is an abundant number, since it is smaller than the sum of its proper divisors (28030278).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21856122 is a wasteful number, since it uses less digits than its factorization.

21856122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10987 (or 10981 counting only the distinct ones).

The product of its digits is 1920, while the sum is 27.

The square root of 21856122 is about 4675.0531547780. The cubic root of 21856122 is about 279.5917605190.

The spelling of 21856122 in words is "twenty-one million, eight hundred fifty-six thousand, one hundred twenty-two".