20101231 has 4 divisors (see below), whose sum is σ = 20279232. Its totient is φ = 19923232.

The previous prime is 20101229. The next prime is 20101247. The reversal of 20101231 is 13210102.

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 20101231 - 2¹ = 20101229 is a prime.

It is a super-2 number, since 2×20101231² = 808118975430722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20101201) 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, 88831 + ... + 89056.

It is an arithmetic number, because the mean of its divisors is an integer number (5069808).

Almost surely, 2^20101231 is an apocalyptic number.

20101231 is a deficient number, since it is larger than the sum of its proper divisors (178001).

20101231 is a wasteful number, since it uses less digits than its factorization.

20101231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178000.

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

The square root of 20101231 is about 4483.4396393840. The cubic root of 20101231 is about 271.8989631584.

Adding to 20101231 its reverse (13210102), we get a palindrome (33311333).

The spelling of 20101231 in words is "twenty million, one hundred one thousand, two hundred thirty-one".