1771981 has 2 divisors, whose sum is σ = 1771982. Its totient is φ = 1771980.

The previous prime is 1771963. The next prime is 1771993. The reversal of 1771981 is 1891771.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1512900 + 259081 = 1230^2 + 509^2 .

It is a cyclic number.

It is not a de Polignac number, because 1771981 - 2¹⁹ = 1247693 is a prime.

It is a super-2 number, since 2×1771981² = 6279833328722, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1771481) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 885990 + 885991.

It is an arithmetic number, because the mean of its divisors is an integer number (885991).

2^1771981 is an apocalyptic number.

It is an amenable number.

1771981 is a deficient number, since it is larger than the sum of its proper divisors (1).

1771981 is an equidigital number, since it uses as much as digits as its factorization.

1771981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3528, while the sum is 34.

The square root of 1771981 is about 1331.1577667579. The cubic root of 1771981 is about 121.0095614328.

The spelling of 1771981 in words is "one million, seven hundred seventy-one thousand, nine hundred eighty-one".