165541639 has 2 divisors, whose sum is σ = 165541640. Its totient is φ = 165541638.

The previous prime is 165541637. The next prime is 165541709. The reversal of 165541639 is 936145561.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 165541639 - 2¹ = 165541637 is a prime.

Together with 165541637, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165541637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82770819 + 82770820.

It is an arithmetic number, because the mean of its divisors is an integer number (82770820).

Almost surely, 2^165541639 is an apocalyptic number.

165541639 is a deficient number, since it is larger than the sum of its proper divisors (1).

165541639 is an equidigital number, since it uses as much as digits as its factorization.

165541639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 97200, while the sum is 40.

The square root of 165541639 is about 12866.2985741821. The cubic root of 165541639 is about 549.0801583460.

The spelling of 165541639 in words is "one hundred sixty-five million, five hundred forty-one thousand, six hundred thirty-nine".