20051231 has 2 divisors, whose sum is σ = 20051232. Its totient is φ = 20051230.

The previous prime is 20051221. The next prime is 20051237. The reversal of 20051231 is 13215002.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20051231 - 2¹⁰ = 20050207 is a prime.

It is a super-2 number, since 2×20051231² = 804103729230722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20051237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10025615 + 10025616.

It is an arithmetic number, because the mean of its divisors is an integer number (10025616).

Almost surely, 2^20051231 is an apocalyptic number.

20051231 is a deficient number, since it is larger than the sum of its proper divisors (1).

20051231 is an equidigital number, since it uses as much as digits as its factorization.

20051231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 20051231 is about 4477.8600916063. The cubic root of 20051231 is about 271.6733345915.

Adding to 20051231 its reverse (13215002), we get a palindrome (33266233).

The spelling of 20051231 in words is "twenty million, fifty-one thousand, two hundred thirty-one".