21797888 has 44 divisors (see below), whose sum is σ = 49815792. Its totient is φ = 9338880.

The previous prime is 21797869. The next prime is 21797891. The reversal of 21797888 is 88879712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5648 + ... + 8688.

Almost surely, 2^21797888 is an apocalyptic number.

21797888 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 21797888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24907896).

21797888 is an abundant number, since it is smaller than the sum of its proper divisors (28017904).

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

21797888 is an equidigital number, since it uses as much as digits as its factorization.

21797888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3068 (or 3050 counting only the distinct ones).

The product of its digits is 451584, while the sum is 50.

The square root of 21797888 is about 4668.8208361427. The cubic root of 21797888 is about 279.3432225499.

The spelling of 21797888 in words is "twenty-one million, seven hundred ninety-seven thousand, eight hundred eighty-eight".