21260780 has 12 divisors (see below), whose sum is σ = 44647680. Its totient is φ = 8504304.

The previous prime is 21260749. The next prime is 21260797. The reversal of 21260780 is 8706212.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 531500 + ... + 531539.

It is an arithmetic number, because the mean of its divisors is an integer number (3720640).

Almost surely, 2^21260780 is an apocalyptic number.

21260780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21260780 is an abundant number, since it is smaller than the sum of its proper divisors (23386900).

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

21260780 is a wasteful number, since it uses less digits than its factorization.

21260780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1063048 (or 1063046 counting only the distinct ones).

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

The square root of 21260780 is about 4610.9413355626. The cubic root of 21260780 is about 277.0297421873.

Adding to 21260780 its reverse (8706212), we get a palindrome (29966992).

The spelling of 21260780 in words is "twenty-one million, two hundred sixty thousand, seven hundred eighty".