20237981 has 2 divisors, whose sum is σ = 20237982. Its totient is φ = 20237980.

The previous prime is 20237963. The next prime is 20237989. The reversal of 20237981 is 18973202.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16532356 + 3705625 = 4066^2 + 1925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20237981 is a prime.

It is a super-2 number, since 2×20237981² = 819151749912722, which contains 22 as substring.

It is equal to p_1284746 and since 20237981 and 1284746 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20237989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10118990 + 10118991.

It is an arithmetic number, because the mean of its divisors is an integer number (10118991).

Almost surely, 2^20237981 is an apocalyptic number.

It is an amenable number.

20237981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20237981 is an equidigital number, since it uses as much as digits as its factorization.

20237981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20237981 is about 4498.6643573399. The cubic root of 20237981 is about 272.5141523946.

It can be divided in two parts, 202 and 37981, that added together give a palindrome (38183).

The spelling of 20237981 in words is "twenty million, two hundred thirty-seven thousand, nine hundred eighty-one".