20790021 has 8 divisors (see below), whose sum is σ = 31680064. Its totient is φ = 11880000.

The previous prime is 20790017. The next prime is 20790023. The reversal of 20790021 is 12009702.

It is a happy number.

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

It is not a de Polignac number, because 20790021 - 2² = 20790017 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 990001 = 20790021 / (2 + 0 + 7 + 9 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20790021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20790023) 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, 494980 + ... + 495021.

It is an arithmetic number, because the mean of its divisors is an integer number (3960008).

Almost surely, 2^20790021 is an apocalyptic number.

20790021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20790021 is a deficient number, since it is larger than the sum of its proper divisors (10890043).

20790021 is an equidigital number, since it uses as much as digits as its factorization.

20790021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 990011.

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 20790021 is about 4559.6075489015. The cubic root of 20790021 is about 274.9697862123.

Adding to 20790021 its reverse (12009702), we get a palindrome (32799723).

The spelling of 20790021 in words is "twenty million, seven hundred ninety thousand, twenty-one".