21185530 has 16 divisors (see below), whose sum is σ = 39792384. Its totient is φ = 8105680.

The previous prime is 21185473. The next prime is 21185533. The reversal of 21185530 is 3558112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21185495 and 21185504.

It is not an unprimeable number, because it can be changed into a prime (21185533) 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 7 ways as a sum of consecutive naturals, for example, 45826 + ... + 46285.

It is an arithmetic number, because the mean of its divisors is an integer number (2487024).

Almost surely, 2^21185530 is an apocalyptic number.

21185530 is a deficient number, since it is larger than the sum of its proper divisors (18606854).

21185530 is a wasteful number, since it uses less digits than its factorization.

21185530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92141.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 21185530 is about 4602.7741634801. The cubic root of 21185530 is about 276.7025178941.

The spelling of 21185530 in words is "twenty-one million, one hundred eighty-five thousand, five hundred thirty".