51781181 has 2 divisors, whose sum is σ = 51781182. Its totient is φ = 51781180.

The previous prime is 51781157. The next prime is 51781199. The reversal of 51781181 is 18118715.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49632025 + 2149156 = 7045^2 + 1466^2 .

It is a cyclic number.

It is not a de Polignac number, because 51781181 - 2⁶ = 51781117 is a prime.

It is a super-2 number, since 2×51781181² = 5362581411509522, 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 (51781111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25890590 + 25890591.

It is an arithmetic number, because the mean of its divisors is an integer number (25890591).

Almost surely, 2^51781181 is an apocalyptic number.

It is an amenable number.

51781181 is a deficient number, since it is larger than the sum of its proper divisors (1).

51781181 is an equidigital number, since it uses as much as digits as its factorization.

51781181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2240, while the sum is 32.

The square root of 51781181 is about 7195.9141879264. The cubic root of 51781181 is about 372.7268255020.

Adding to 51781181 its reverse (18118715), we get a palindrome (69899896).

The spelling of 51781181 in words is "fifty-one million, seven hundred eighty-one thousand, one hundred eighty-one".