165964781 has 2 divisors, whose sum is σ = 165964782. Its totient is φ = 165964780.

The previous prime is 165964763. The next prime is 165964787. The reversal of 165964781 is 187469561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 157502500 + 8462281 = 12550^2 + 2909^2 .

It is a cyclic number.

It is not a de Polignac number, because 165964781 - 2¹⁴ = 165948397 is a prime.

It is a super-2 number, since 2×165964781² = 55088617064755922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165964787) 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, 82982390 + 82982391.

It is an arithmetic number, because the mean of its divisors is an integer number (82982391).

Almost surely, 2^165964781 is an apocalyptic number.

It is an amenable number.

165964781 is a deficient number, since it is larger than the sum of its proper divisors (1).

165964781 is an equidigital number, since it uses as much as digits as its factorization.

165964781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 47.

The square root of 165964781 is about 12882.7318919552. The cubic root of 165964781 is about 549.5475960200.

The spelling of 165964781 in words is "one hundred sixty-five million, nine hundred sixty-four thousand, seven hundred eighty-one".