21559730 has 16 divisors (see below), whose sum is σ = 38963160. Its totient is φ = 8589312.

The previous prime is 21559709. The next prime is 21559739. The reversal of 21559730 is 3795512.

It can be written as a sum of positive squares in 4 ways, for example, as 21446161 + 113569 = 4631^2 + 337^2 .

It is not an unprimeable number, because it can be changed into a prime (21559739) 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, 1625 + ... + 6764.

Almost surely, 2^21559730 is an apocalyptic number.

21559730 is a deficient number, since it is larger than the sum of its proper divisors (17403430).

21559730 is a wasteful number, since it uses less digits than its factorization.

21559730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8653.

The product of its (nonzero) digits is 9450, while the sum is 32.

The square root of 21559730 is about 4643.2456320983. The cubic root of 21559730 is about 278.3221512553.

The spelling of 21559730 in words is "twenty-one million, five hundred fifty-nine thousand, seven hundred thirty".