165131611 has 4 divisors (see below), whose sum is σ = 165728032. Its totient is φ = 164535192.

The previous prime is 165131609. The next prime is 165131663. The reversal of 165131611 is 116131561.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 165131611 - 2¹ = 165131609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165131311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 297795 + ... + 298348.

It is an arithmetic number, because the mean of its divisors is an integer number (41432008).

Almost surely, 2^165131611 is an apocalyptic number.

165131611 is a deficient number, since it is larger than the sum of its proper divisors (596421).

165131611 is an equidigital number, since it uses as much as digits as its factorization.

165131611 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 596420.

The product of its digits is 540, while the sum is 25.

The square root of 165131611 is about 12850.3545087285. The cubic root of 165131611 is about 548.6264469667.

Subtracting from 165131611 its reverse (116131561), we obtain a triangular number (49000050 = T₉₈₉₉).

The spelling of 165131611 in words is "one hundred sixty-five million, one hundred thirty-one thousand, six hundred eleven".