21280760 has 32 divisors (see below), whose sum is σ = 50403600. Its totient is φ = 8064000.

The previous prime is 21280757. The next prime is 21280771. The reversal of 21280760 is 6708212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13241 + ... + 14760.

Almost surely, 2^21280760 is an apocalyptic number.

21280760 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21280760 is an abundant number, since it is smaller than the sum of its proper divisors (29122840).

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

21280760 is a wasteful number, since it uses less digits than its factorization.

21280760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28031 (or 28027 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 26.

The square root of 21280760 is about 4613.1074125799. The cubic root of 21280760 is about 277.1164953745.

Adding to 21280760 its reverse (6708212), we get a palindrome (27988972).

The spelling of 21280760 in words is "twenty-one million, two hundred eighty thousand, seven hundred sixty".