21366420 has 48 divisors (see below), whose sum is σ = 60963840. Its totient is φ = 5589376.

The previous prime is 21366407. The next prime is 21366463. The reversal of 21366420 is 2466312.

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, 180 + ... + 6539.

It is an arithmetic number, because the mean of its divisors is an integer number (1270080).

Almost surely, 2^21366420 is an apocalyptic number.

21366420 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 21366420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30481920).

21366420 is an abundant number, since it is smaller than the sum of its proper divisors (39597420).

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

21366420 is a wasteful number, since it uses less digits than its factorization.

21366420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6784 (or 6782 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 21366420 is about 4622.3825025629. The cubic root of 21366420 is about 277.4878170124.

The spelling of 21366420 in words is "twenty-one million, three hundred sixty-six thousand, four hundred twenty".