21533460 has 96 divisors (see below), whose sum is σ = 68396160. Its totient is φ = 5018112.

The previous prime is 21533459. The next prime is 21533471. The reversal of 21533460 is 6433512.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21533460.

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, 14094 + ... + 15546.

It is an arithmetic number, because the mean of its divisors is an integer number (712460).

Almost surely, 2^21533460 is an apocalyptic number.

21533460 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 21533460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34198080).

21533460 is an abundant number, since it is smaller than the sum of its proper divisors (46862700).

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

21533460 is a wasteful number, since it uses less digits than its factorization.

21533460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1497 (or 1495 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21533460 is about 4640.4159296339. The cubic root of 21533460 is about 278.2090624154.

Adding to 21533460 its reverse (6433512), we get a palindrome (27966972).

The spelling of 21533460 in words is "twenty-one million, five hundred thirty-three thousand, four hundred sixty".