21316860 has 144 divisors (see below), whose sum is σ = 71285760. Its totient is φ = 5132160.

The previous prime is 21316859. The next prime is 21316891. The reversal of 21316860 is 6861312.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 78525 + ... + 78795.

It is an arithmetic number, because the mean of its divisors is an integer number (495040).

Almost surely, 2^21316860 is an apocalyptic number.

21316860 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 21316860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35642880).

21316860 is an abundant number, since it is smaller than the sum of its proper divisors (49968900).

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

21316860 is a wasteful number, since it uses less digits than its factorization.

21316860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 323 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21316860 is about 4617.0185184814. The cubic root of 21316860 is about 277.2731040364.

The spelling of 21316860 in words is "twenty-one million, three hundred sixteen thousand, eight hundred sixty".