21236280 has 64 divisors (see below), whose sum is σ = 68614560. Its totient is φ = 5227008.

The previous prime is 21236273. The next prime is 21236311. The reversal of 21236280 is 8263212.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21236280.

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, 5247 + ... + 8366.

Almost surely, 2^21236280 is an apocalyptic number.

21236280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21236280 is an abundant number, since it is smaller than the sum of its proper divisors (47378280).

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

21236280 is a wasteful number, since it uses less digits than its factorization.

21236280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13640 (or 13636 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21236280 is about 4608.2838454245. The cubic root of 21236280 is about 276.9232889362.

Adding to 21236280 its reverse (8263212), we get a palindrome (29499492).

The spelling of 21236280 in words is "twenty-one million, two hundred thirty-six thousand, two hundred eighty".