66161945 has 4 divisors (see below), whose sum is σ = 79394340. Its totient is φ = 52929552.

The previous prime is 66161941. The next prime is 66161983. The reversal of 66161945 is 54916166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 54916166 = 2 ⋅27458083.

It can be written as a sum of positive squares in 2 ways, for example, as 38588944 + 27573001 = 6212^2 + 5251^2 .

It is a cyclic number.

It is not a de Polignac number, because 66161945 - 2² = 66161941 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 66161899 and 66161908.

It is not an unprimeable number, because it can be changed into a prime (66161941) 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, 6616190 + ... + 6616199.

It is an arithmetic number, because the mean of its divisors is an integer number (19848585).

Almost surely, 2^66161945 is an apocalyptic number.

It is an amenable number.

66161945 is a deficient number, since it is larger than the sum of its proper divisors (13232395).

66161945 is a wasteful number, since it uses less digits than its factorization.

66161945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13232394.

The product of its digits is 38880, while the sum is 38.

The square root of 66161945 is about 8133.9993238259. Note that the first 3 decimals coincide. The cubic root of 66161945 is about 404.4542667386.

The spelling of 66161945 in words is "sixty-six million, one hundred sixty-one thousand, nine hundred forty-five".