21152280 has 64 divisors (see below), whose sum is σ = 63763200. Its totient is φ = 5613440.

The previous prime is 21152239. The next prime is 21152291. The reversal of 21152280 is 8225112.

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 15 ways as a sum of consecutive naturals, for example, 42835 + ... + 43325.

It is an arithmetic number, because the mean of its divisors is an integer number (996300).

Almost surely, 2^21152280 is an apocalyptic number.

21152280 is a gapful number since it is divisible by the number (20) 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 21152280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31881600).

21152280 is an abundant number, since it is smaller than the sum of its proper divisors (42610920).

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

21152280 is a wasteful number, since it uses less digits than its factorization.

21152280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864 (or 860 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21152280 is about 4599.1607930143. The cubic root of 21152280 is about 276.5576835639.

Adding to 21152280 its reverse (8225112), we get a palindrome (29377392).

The spelling of 21152280 in words is "twenty-one million, one hundred fifty-two thousand, two hundred eighty".