21811712 has 80 divisors (see below), whose sum is σ = 48981240. Its totient is φ = 9633792.

The previous prime is 21811679. The next prime is 21811717. The reversal of 21811712 is 21711812.

It can be written as a sum of positive squares in 4 ways, for example, as 8386816 + 13424896 = 2896^2 + 3664^2 .

It is not an unprimeable number, because it can be changed into a prime (21811717) 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, 192968 + ... + 193080.

Almost surely, 2^21811712 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21811712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24490620).

21811712 is an abundant number, since it is smaller than the sum of its proper divisors (27169528).

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

21811712 is a wasteful number, since it uses less digits than its factorization.

21811712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 157 counting only the distinct ones).

The product of its digits is 224, while the sum is 23.

The square root of 21811712 is about 4670.3010609596. The cubic root of 21811712 is about 279.4022622859.

The spelling of 21811712 in words is "twenty-one million, eight hundred eleven thousand, seven hundred twelve".