1231381 has 2 divisors, whose sum is σ = 1231382. Its totient is φ = 1231380.

The previous prime is 1231379. The next prime is 1231387. The reversal of 1231381 is 1831321.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1102500 + 128881 = 1050^2 + 359^2 .

It is a cyclic number.

It is not a de Polignac number, because 1231381 - 2¹ = 1231379 is a prime.

It is a super-2 number, since 2×1231381² = 3032598334322, which contains 22 as substring.

Together with 1231379, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1231387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 615690 + 615691.

It is an arithmetic number, because the mean of its divisors is an integer number (615691).

2^1231381 is an apocalyptic number.

It is an amenable number.

1231381 is a deficient number, since it is larger than the sum of its proper divisors (1).

1231381 is an equidigital number, since it uses as much as digits as its factorization.

1231381 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 1231381 is about 1109.6760788627. The cubic root of 1231381 is about 107.1842111688.

The spelling of 1231381 in words is "one million, two hundred thirty-one thousand, three hundred eighty-one".