21105530 has 8 divisors (see below), whose sum is σ = 37989972. Its totient is φ = 8442208.

The previous prime is 21105509. The next prime is 21105547. The reversal of 21105530 is 3550112.

It can be written as a sum of positive squares in 2 ways, for example, as 20079361 + 1026169 = 4481^2 + 1013^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 21105499 and 21105508.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1055267 + ... + 1055286.

Almost surely, 2^21105530 is an apocalyptic number.

21105530 is a deficient number, since it is larger than the sum of its proper divisors (16884442).

21105530 is a wasteful number, since it uses less digits than its factorization.

21105530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2110560.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21105530 is about 4594.0755326834. The cubic root of 21105530 is about 276.3537873638.

Adding to 21105530 its reverse (3550112), we get a palindrome (24655642).

The spelling of 21105530 in words is "twenty-one million, one hundred five thousand, five hundred thirty".