20351381 has 2 divisors, whose sum is σ = 20351382. Its totient is φ = 20351380.

The previous prime is 20351371. The next prime is 20351437. The reversal of 20351381 is 18315302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12460900 + 7890481 = 3530^2 + 2809^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20351381 is a prime.

It is a super-2 number, since 2×20351381² = 828357417214322, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20351371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10175690 + 10175691.

It is an arithmetic number, because the mean of its divisors is an integer number (10175691).

Almost surely, 2^20351381 is an apocalyptic number.

It is an amenable number.

20351381 is a deficient number, since it is larger than the sum of its proper divisors (1).

20351381 is an equidigital number, since it uses as much as digits as its factorization.

20351381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 20351381 is about 4511.2504918260. The cubic root of 20351381 is about 273.0221998433.

Adding to 20351381 its reverse (18315302), we get a palindrome (38666683).

The spelling of 20351381 in words is "twenty million, three hundred fifty-one thousand, three hundred eighty-one".