20121131 has 4 divisors (see below), whose sum is σ = 20131272. Its totient is φ = 20110992.

The previous prime is 20121121. The next prime is 20121137. The reversal of 20121131 is 13112102.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20121131 is a prime.

It is a super-2 number, since 2×20121131² = 809719825438322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20121137) 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 3 ways as a sum of consecutive naturals, for example, 1010 + ... + 6423.

It is an arithmetic number, because the mean of its divisors is an integer number (5032818).

Almost surely, 2^20121131 is an apocalyptic number.

20121131 is a deficient number, since it is larger than the sum of its proper divisors (10141).

20121131 is an equidigital number, since it uses as much as digits as its factorization.

20121131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10140.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 20121131 is about 4485.6583686233. The cubic root of 20121131 is about 271.9886592374.

Adding to 20121131 its reverse (13112102), we get a palindrome (33233233).

The spelling of 20121131 in words is "twenty million, one hundred twenty-one thousand, one hundred thirty-one".