165666505403 has 24 divisors (see below), whose sum is σ = 197493633792. Its totient is φ = 136099380384.

The previous prime is 165666505391. The next prime is 165666505423. The reversal of 165666505403 is 304505666561.

It is not a de Polignac number, because 165666505403 - 2⁶ = 165666505339 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165666505423) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 513050 + ... + 771072.

It is an arithmetic number, because the mean of its divisors is an integer number (8228901408).

Almost surely, 2^165666505403 is an apocalyptic number.

165666505403 is a deficient number, since it is larger than the sum of its proper divisors (31827128389).

165666505403 is an equidigital number, since it uses as much as digits as its factorization.

165666505403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258171 (or 258134 counting only the distinct ones).

The product of its (nonzero) digits is 1944000, while the sum is 47.

The spelling of 165666505403 in words is "one hundred sixty-five billion, six hundred sixty-six million, five hundred five thousand, four hundred three".