21827988 has 96 divisors (see below), whose sum is σ = 69681920. Its totient is φ = 5754240.

The previous prime is 21827977. The next prime is 21828029. The reversal of 21827988 is 88972812.

It is a happy number.

It is a super-2 number, since 2×21827988² = 952922120256288, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8718 + ... + 10938.

Almost surely, 2^21827988 is an apocalyptic number.

21827988 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21827988, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34840960).

21827988 is an abundant number, since it is smaller than the sum of its proper divisors (47853932).

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

21827988 is a wasteful number, since it uses less digits than its factorization.

21827988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2254 (or 2246 counting only the distinct ones).

The product of its digits is 129024, while the sum is 45.

The square root of 21827988 is about 4672.0432361013. The cubic root of 21827988 is about 279.4717420919.

The spelling of 21827988 in words is "twenty-one million, eight hundred twenty-seven thousand, nine hundred eighty-eight".