21243460 has 72 divisors (see below), whose sum is σ = 53003160. Its totient is φ = 7128576.

The previous prime is 21243437. The next prime is 21243473. The reversal of 21243460 is 6434212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8398404 + 12845056 = 2898^2 + 3584^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51736 + ... + 52144.

It is an arithmetic number, because the mean of its divisors is an integer number (736155).

Almost surely, 2^21243460 is an apocalyptic number.

21243460 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 21243460, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26501580).

21243460 is an abundant number, since it is smaller than the sum of its proper divisors (31759700).

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

21243460 is a wasteful number, since it uses less digits than its factorization.

21243460 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485 (or 476 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 21243460 is about 4609.0628114618. The cubic root of 21243460 is about 276.9544947339.

Adding to 21243460 its reverse (6434212), we get a palindrome (27677672).

The spelling of 21243460 in words is "twenty-one million, two hundred forty-three thousand, four hundred sixty".