20021091 has 16 divisors (see below), whose sum is σ = 27264384. Its totient is φ = 13065984.

The previous prime is 20021081. The next prime is 20021093. The reversal of 20021091 is 19012002.

It is a happy number.

It is not a de Polignac number, because 20021091 - 2⁵ = 20021059 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20021091.

It is not an unprimeable number, because it can be changed into a prime (20021093) 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, 30816 + ... + 31458.

It is an arithmetic number, because the mean of its divisors is an integer number (1704024).

Almost surely, 2^20021091 is an apocalyptic number.

20021091 is a deficient number, since it is larger than the sum of its proper divisors (7243293).

20021091 is a wasteful number, since it uses less digits than its factorization.

20021091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 850.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 20021091 is about 4474.4933791436. The cubic root of 20021091 is about 271.5371444420.

Adding to 20021091 its reverse (19012002), we get a palindrome (39033093).

The spelling of 20021091 in words is "twenty million, twenty-one thousand, ninety-one".