19866065 has 4 divisors (see below), whose sum is σ = 23839284. Its totient is φ = 15892848.

The previous prime is 19866031. The next prime is 19866113. The reversal of 19866065 is 56066891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56066891 = 19 ⋅2950889.

It can be written as a sum of positive squares in 2 ways, for example, as 2660161 + 17205904 = 1631^2 + 4148^2 .

It is a cyclic number.

It is not a de Polignac number, because 19866065 - 2¹² = 19861969 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1986602 + ... + 1986611.

It is an arithmetic number, because the mean of its divisors is an integer number (5959821).

Almost surely, 2^19866065 is an apocalyptic number.

It is an amenable number.

19866065 is a deficient number, since it is larger than the sum of its proper divisors (3973219).

19866065 is an equidigital number, since it uses as much as digits as its factorization.

19866065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3973218.

The product of its (nonzero) digits is 77760, while the sum is 41.

The square root of 19866065 is about 4457.1364125411. The cubic root of 19866065 is about 270.8344781543.

The spelling of 19866065 in words is "nineteen million, eight hundred sixty-six thousand, sixty-five".