20730021 has 16 divisors (see below), whose sum is σ = 31518144. Its totient is φ = 12006144.

The previous prime is 20730011. The next prime is 20730037. The reversal of 20730021 is 12003702.

It is not a de Polignac number, because 20730021 - 2¹⁵ = 20697253 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20730011) 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 15 ways as a sum of consecutive naturals, for example, 14971 + ... + 16296.

It is an arithmetic number, because the mean of its divisors is an integer number (1969884).

Almost surely, 2^20730021 is an apocalyptic number.

It is an amenable number.

20730021 is a deficient number, since it is larger than the sum of its proper divisors (10788123).

20730021 is a wasteful number, since it uses less digits than its factorization.

20730021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31300.

The product of its (nonzero) digits is 84, while the sum is 15.

The square root of 20730021 is about 4553.0232812934. The cubic root of 20730021 is about 274.7050104027.

Adding to 20730021 its reverse (12003702), we get a palindrome (32733723).

The spelling of 20730021 in words is "twenty million, seven hundred thirty thousand, twenty-one".