20001231 has 24 divisors (see below), whose sum is σ = 31584384. Its totient is φ = 12142080.

The previous prime is 20001227. The next prime is 20001239. The reversal of 20001231 is 13210002.

It is a happy number.

It is not a de Polignac number, because 20001231 - 2² = 20001227 is a prime.

It is a super-2 number, since 2×20001231² = 800098483030722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001239) 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 23 ways as a sum of consecutive naturals, for example, 2635 + ... + 6851.

It is an arithmetic number, because the mean of its divisors is an integer number (1316016).

Almost surely, 2^20001231 is an apocalyptic number.

20001231 is a deficient number, since it is larger than the sum of its proper divisors (11583153).

20001231 is a wasteful number, since it uses less digits than its factorization.

20001231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4271 (or 4268 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 20001231 is about 4472.2735828659. The cubic root of 20001231 is about 271.4473306254.

Adding to 20001231 its reverse (13210002), we get a palindrome (33211233).

The spelling of 20001231 in words is "twenty million, one thousand, two hundred thirty-one".