21396280 has 64 divisors (see below), whose sum is σ = 51840000. Its totient is φ = 7922304.

The previous prime is 21396269. The next prime is 21396289. The reversal of 21396280 is 8269312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21396289) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35421 + ... + 36019.

It is an arithmetic number, because the mean of its divisors is an integer number (810000).

Almost surely, 2^21396280 is an apocalyptic number.

21396280 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 21396280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25920000).

21396280 is an abundant number, since it is smaller than the sum of its proper divisors (30443720).

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

21396280 is a wasteful number, since it uses less digits than its factorization.

21396280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 676 (or 672 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 21396280 is about 4625.6113109512. The cubic root of 21396280 is about 277.6170217702.

The spelling of 21396280 in words is "twenty-one million, three hundred ninety-six thousand, two hundred eighty".