21544660 has 12 divisors (see below), whose sum is σ = 45243828. Its totient is φ = 8617856.

The previous prime is 21544631. The next prime is 21544669. The reversal of 21544660 is 6644512.

It can be written as a sum of positive squares in 2 ways, for example, as 14638276 + 6906384 = 3826^2 + 2628^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21544669) 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, 538597 + ... + 538636.

It is an arithmetic number, because the mean of its divisors is an integer number (3770319).

Almost surely, 2^21544660 is an apocalyptic number.

21544660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21544660 is an abundant number, since it is smaller than the sum of its proper divisors (23699168).

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

21544660 is a wasteful number, since it uses less digits than its factorization.

21544660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1077242 (or 1077240 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 21544660 is about 4641.6225611310. The cubic root of 21544660 is about 278.2572881601.

The spelling of 21544660 in words is "twenty-one million, five hundred forty-four thousand, six hundred sixty".