20013881 has 2 divisors, whose sum is σ = 20013882. Its totient is φ = 20013880.

The previous prime is 20013823. The next prime is 20013883. The reversal of 20013881 is 18831002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19536400 + 477481 = 4420^2 + 691^2 .

It is a cyclic number.

It is not a de Polignac number, because 20013881 - 2¹⁰ = 20012857 is a prime.

It is a super-2 number, since 2×20013881² = 801110865364322, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 20013883, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20013883) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10006940 + 10006941.

It is an arithmetic number, because the mean of its divisors is an integer number (10006941).

Almost surely, 2^20013881 is an apocalyptic number.

It is an amenable number.

20013881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20013881 is an equidigital number, since it uses as much as digits as its factorization.

20013881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 20013881 is about 4473.6876287913. The cubic root of 20013881 is about 271.5045451883.

Adding to 20013881 its reverse (18831002), we get a palindrome (38844883).

The spelling of 20013881 in words is "twenty million, thirteen thousand, eight hundred eighty-one".