20501381 has 2 divisors, whose sum is σ = 20501382. Its totient is φ = 20501380.

The previous prime is 20501363. The next prime is 20501389. The reversal of 20501381 is 18310502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17297281 + 3204100 = 4159^2 + 1790^2 .

It is a cyclic number.

It is not a de Polignac number, because 20501381 - 2¹⁰ = 20500357 is a prime.

It is a super-2 number, since 2×20501381² = 840613245814322, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20501389) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10250690 + 10250691.

It is an arithmetic number, because the mean of its divisors is an integer number (10250691).

Almost surely, 2^20501381 is an apocalyptic number.

It is an amenable number.

20501381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20501381 is an equidigital number, since it uses as much as digits as its factorization.

20501381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 20501381 is about 4527.8450724379. The cubic root of 20501381 is about 273.6913292806.

Adding to 20501381 its reverse (18310502), we get a palindrome (38811883).

The spelling of 20501381 in words is "twenty million, five hundred one thousand, three hundred eighty-one".