20021191 has 4 divisors (see below), whose sum is σ = 20122000. Its totient is φ = 19920384.

The previous prime is 20021171. The next prime is 20021203. The reversal of 20021191 is 19112002.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20021191 - 2⁵ = 20021159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50106 + ... + 50503.

It is an arithmetic number, because the mean of its divisors is an integer number (5030500).

Almost surely, 2^20021191 is an apocalyptic number.

20021191 is a deficient number, since it is larger than the sum of its proper divisors (100809).

20021191 is a wasteful number, since it uses less digits than its factorization.

20021191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100808.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 20021191 is about 4474.5045535791. The cubic root of 20021191 is about 271.5375965264.

Adding to 20021191 its reverse (19112002), we get a palindrome (39133193).

The spelling of 20021191 in words is "twenty million, twenty-one thousand, one hundred ninety-one".