21289960 has 16 divisors (see below), whose sum is σ = 47902500. Its totient is φ = 8515968.

The previous prime is 21289949. The next prime is 21289969. The reversal of 21289960 is 6998212.

It can be written as a sum of positive squares in 2 ways, for example, as 21178404 + 111556 = 4602^2 + 334^2 .

It is not an unprimeable number, because it can be changed into a prime (21289969) 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 3 ways as a sum of consecutive naturals, for example, 266085 + ... + 266164.

Almost surely, 2^21289960 is an apocalyptic number.

21289960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21289960 is an abundant number, since it is smaller than the sum of its proper divisors (26612540).

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

21289960 is a wasteful number, since it uses less digits than its factorization.

21289960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532260 (or 532256 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21289960 is about 4614.1044634902. The cubic root of 21289960 is about 277.1564235296.

The spelling of 21289960 in words is "twenty-one million, two hundred eighty-nine thousand, nine hundred sixty".