21104660 has 12 divisors (see below), whose sum is σ = 44319828. Its totient is φ = 8441856.

The previous prime is 21104647. The next prime is 21104669. The reversal of 21104660 is 6640112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 5769604 + 15335056 = 2402^2 + 3916^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 1055233 = 21104660 / (2 + 1 + 1 + 0 + 4 + 6 + 6 + 0).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21104669) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527597 + ... + 527636.

It is an arithmetic number, because the mean of its divisors is an integer number (3693319).

Almost surely, 2^21104660 is an apocalyptic number.

21104660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21104660 is an abundant number, since it is smaller than the sum of its proper divisors (23215168).

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

21104660 is a wasteful number, since it uses less digits than its factorization.

21104660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055242 (or 1055240 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21104660 is about 4593.9808445400. The cubic root of 21104660 is about 276.3499900795.

Adding to 21104660 its reverse (6640112), we get a palindrome (27744772).

The spelling of 21104660 in words is "twenty-one million, one hundred four thousand, six hundred sixty".