1966431781 has 2 divisors, whose sum is σ = 1966431782. Its totient is φ = 1966431780.

The previous prime is 1966431707. The next prime is 1966431787. The reversal of 1966431781 is 1871346691.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1064390625 + 902041156 = 32625^2 + 30034^2 .

It is a cyclic number.

It is not a de Polignac number, because 1966431781 - 2²¹ = 1964334629 is a prime.

It is a super-2 number, since 2×1966431781² = 7733707898653663922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1966431787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 983215890 + 983215891.

It is an arithmetic number, because the mean of its divisors is an integer number (983215891).

Almost surely, 2^1966431781 is an apocalyptic number.

It is an amenable number.

1966431781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1966431781 is an equidigital number, since it uses as much as digits as its factorization.

1966431781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 46.

The square root of 1966431781 is about 44344.4673099136. The cubic root of 1966431781 is about 1252.8323573010.

The spelling of 1966431781 in words is "one billion, nine hundred sixty-six million, four hundred thirty-one thousand, seven hundred eighty-one".