21252730 has 8 divisors (see below), whose sum is σ = 38254932. Its totient is φ = 8501088.

The previous prime is 21252727. The next prime is 21252739. The reversal of 21252730 is 3725212.

It can be written as a sum of positive squares in 2 ways, for example, as 19210689 + 2042041 = 4383^2 + 1429^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21252739) 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 3 ways as a sum of consecutive naturals, for example, 1062627 + ... + 1062646.

Almost surely, 2^21252730 is an apocalyptic number.

21252730 is a deficient number, since it is larger than the sum of its proper divisors (17002202).

21252730 is a wasteful number, since it uses less digits than its factorization.

21252730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2125280.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21252730 is about 4610.0683292116. The cubic root of 21252730 is about 276.9947737157.

Adding to 21252730 its reverse (3725212), we get a palindrome (24977942).

The spelling of 21252730 in words is "twenty-one million, two hundred fifty-two thousand, seven hundred thirty".