1381 has 2 divisors, whose sum is σ = 1382. Its totient is φ = 1380.
The previous prime is 1373. The next prime is 1399. The reversal of 1381 is 1831.
1381 is nontrivially palindromic in base 16.
1381 is an esthetic number in base 16, because in such base its adjacent digits differ by 1.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 1156 + 225 = 34^2 + 15^2 .
It is an emirp because it is prime and its reverse (1831) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 1381 - 23 = 1373 is a prime.
It is a super-2 number, since 2×13812 = 3814322, which contains 22 as substring.
It is a Chen prime.
1381 is an undulating number in base 16.
It is a nialpdrome in base 12 and base 15.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (1301) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 690 + 691.
It is an arithmetic number, because the mean of its divisors is an integer number (691).
1381 is the 24-th centered pentagonal number.
It is an amenable number.
1381 is a deficient number, since it is larger than the sum of its proper divisors (1).
1381 is an equidigital number, since it uses as much as digits as its factorization.
1381 is an evil number, because the sum of its binary digits is even.
The product of its digits is 24, while the sum is 13.
The square root of 1381 is about 37.1618083521. The cubic root of 1381 is about 11.1360513840.
The spelling of 1381 in words is "one thousand, three hundred eighty-one".
• e-mail: info -at- numbersaplenty.com • Privacy notice • done in 0.059 sec. • engine limits •