165664403 has 4 divisors (see below), whose sum is σ = 171008448. Its totient is φ = 160320360.

The previous prime is 165664391. The next prime is 165664409. The reversal of 165664403 is 304466561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 304466561 = 7 ⋅43495223.

It is a cyclic number.

It is not a de Polignac number, because 165664403 - 2¹² = 165660307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165664409) 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, 2671976 + ... + 2672037.

It is an arithmetic number, because the mean of its divisors is an integer number (42752112).

Almost surely, 2^165664403 is an apocalyptic number.

165664403 is a deficient number, since it is larger than the sum of its proper divisors (5344045).

165664403 is an equidigital number, since it uses as much as digits as its factorization.

165664403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5344044.

The product of its (nonzero) digits is 51840, while the sum is 35.

The square root of 165664403 is about 12871.0684482680. The cubic root of 165664403 is about 549.2158555659.

The spelling of 165664403 in words is "one hundred sixty-five million, six hundred sixty-four thousand, four hundred three".