21660530 has 8 divisors (see below), whose sum is σ = 38988972. Its totient is φ = 8664208.

The previous prime is 21660523. The next prime is 21660559. The reversal of 21660530 is 3506612.

It can be written as a sum of positive squares in 2 ways, for example, as 21446161 + 214369 = 4631^2 + 463^2 .

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 = 21660496 and 21660505.

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, 1083017 + ... + 1083036.

Almost surely, 2^21660530 is an apocalyptic number.

21660530 is a deficient number, since it is larger than the sum of its proper divisors (17328442).

21660530 is a wasteful number, since it uses less digits than its factorization.

21660530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2166060.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 21660530 is about 4654.0874508329. The cubic root of 21660530 is about 278.7552312558.

The spelling of 21660530 in words is "twenty-one million, six hundred sixty thousand, five hundred thirty".