61381 has 2 divisors, whose sum is σ = 61382. Its totient is φ = 61380.

The previous prime is 61379. The next prime is 61403. The reversal of 61381 is 18316.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 36100 + 25281 = 190^2 + 159^2 .

It is a cyclic number.

It is not a de Polignac number, because 61381 - 2¹ = 61379 is a prime.

It is a super-2 number, since 2×61381² = 7535254322, which contains 22 as substring.

Together with 61379, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30690 + 30691.

It is an arithmetic number, because the mean of its divisors is an integer number (30691).

2⁶¹³⁸¹ is an apocalyptic number.

It is an amenable number.

61381 is a deficient number, since it is larger than the sum of its proper divisors (1).

61381 is an equidigital number, since it uses as much as digits as its factorization.

61381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 144, while the sum is 19.

The square root of 61381 is about 247.7518920210. The cubic root of 61381 is about 39.4467583704.

Adding to 61381 its reverse (18316), we get a palindrome (79697).

The spelling of 61381 in words is "sixty-one thousand, three hundred eighty-one".