20021131 has 4 divisors (see below), whose sum is σ = 21561232. Its totient is φ = 18481032.

The previous prime is 20021093. The next prime is 20021137. The reversal of 20021131 is 13112002.

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 20021131 - 2⁹ = 20020619 is a prime.

It is a super-2 number, since 2×20021131² = 801691373038322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20021137) 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, 770031 + ... + 770056.

It is an arithmetic number, because the mean of its divisors is an integer number (5390308).

Almost surely, 2^20021131 is an apocalyptic number.

20021131 is a deficient number, since it is larger than the sum of its proper divisors (1540101).

20021131 is a wasteful number, since it uses less digits than its factorization.

20021131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1540100.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 20021131 is about 4474.4978489212. The cubic root of 20021131 is about 271.5373252759.

Adding to 20021131 its reverse (13112002), we get a palindrome (33133133).

The spelling of 20021131 in words is "twenty million, twenty-one thousand, one hundred thirty-one".