21787248 has 80 divisors (see below), whose sum is σ = 65440256. Its totient is φ = 6117120.

The previous prime is 21787237. The next prime is 21787301. The reversal of 21787248 is 84278712.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19965 + ... + 21027.

Almost surely, 2^21787248 is an apocalyptic number.

21787248 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 21787248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32720128).

21787248 is an abundant number, since it is smaller than the sum of its proper divisors (43653008).

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

21787248 is a wasteful number, since it uses less digits than its factorization.

21787248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1142 (or 1136 counting only the distinct ones).

The product of its digits is 50176, while the sum is 39.

The square root of 21787248 is about 4667.6812230485. The cubic root of 21787248 is about 279.2977640844.

The spelling of 21787248 in words is "twenty-one million, seven hundred eighty-seven thousand, two hundred forty-eight".