21045730 has 32 divisors (see below), whose sum is σ = 40124160. Its totient is φ = 7925760.

The previous prime is 21045727. The next prime is 21045737. The reversal of 21045730 is 3754012.

It is not an unprimeable number, because it can be changed into a prime (21045737) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48615 + ... + 49045.

It is an arithmetic number, because the mean of its divisors is an integer number (1253880).

Almost surely, 2^21045730 is an apocalyptic number.

21045730 is a deficient number, since it is larger than the sum of its proper divisors (19078430).

21045730 is a wasteful number, since it uses less digits than its factorization.

21045730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714.

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

The square root of 21045730 is about 4587.5625336337. The cubic root of 21045730 is about 276.0925353096.

Adding to 21045730 its reverse (3754012), we get a palindrome (24799742).

The spelling of 21045730 in words is "twenty-one million, forty-five thousand, seven hundred thirty".