21180730 has 16 divisors (see below), whose sum is σ = 39440520. Its totient is φ = 8180032.

The previous prime is 21180727. The next prime is 21180737. The reversal of 21180730 is 3708112.

It can be written as a sum of positive squares in 4 ways, for example, as 20675209 + 505521 = 4547^2 + 711^2 .

It is not an unprimeable number, because it can be changed into a prime (21180737) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 36229 + ... + 36808.

Almost surely, 2^21180730 is an apocalyptic number.

21180730 is a deficient number, since it is larger than the sum of its proper divisors (18259790).

21180730 is a wasteful number, since it uses less digits than its factorization.

21180730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73073.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21180730 is about 4602.2527092718. The cubic root of 21180730 is about 276.6816188432.

Adding to 21180730 its reverse (3708112), we get a palindrome (24888842).

The spelling of 21180730 in words is "twenty-one million, one hundred eighty thousand, seven hundred thirty".