1391981 has 2 divisors, whose sum is σ = 1391982. Its totient is φ = 1391980.

The previous prime is 1391969. The next prime is 1391989. The reversal of 1391981 is 1891931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 990025 + 401956 = 995^2 + 634^2 .

It is a cyclic number.

It is not a de Polignac number, because 1391981 - 2⁶ = 1391917 is a prime.

It is a super-2 number, since 2×1391981² = 3875222208722, 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 (1391989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 695990 + 695991.

It is an arithmetic number, because the mean of its divisors is an integer number (695991).

2^1391981 is an apocalyptic number.

It is an amenable number.

1391981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1391981 is an equidigital number, since it uses as much as digits as its factorization.

1391981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1944, while the sum is 32.

The square root of 1391981 is about 1179.8224442686. The cubic root of 1391981 is about 111.6548954202.

The spelling of 1391981 in words is "one million, three hundred ninety-one thousand, nine hundred eighty-one".