66155641 has 4 divisors (see below), whose sum is σ = 68436900. Its totient is φ = 63874384.

The previous prime is 66155623. The next prime is 66155647. The reversal of 66155641 is 14655166.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 14655166 = 2 ⋅7327583.

It can be written as a sum of positive squares in 2 ways, for example, as 12924025 + 53231616 = 3595^2 + 7296^2 .

It is a cyclic number.

It is not a de Polignac number, because 66155641 - 2⁷ = 66155513 is a prime.

It is a super-2 number, since 2×66155641² = 8753137672241762, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66155597 and 66155606.

It is not an unprimeable number, because it can be changed into a prime (66155647) 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, 1140586 + ... + 1140643.

It is an arithmetic number, because the mean of its divisors is an integer number (17109225).

Almost surely, 2^66155641 is an apocalyptic number.

It is an amenable number.

66155641 is a deficient number, since it is larger than the sum of its proper divisors (2281259).

66155641 is a wasteful number, since it uses less digits than its factorization.

66155641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2281258.

The product of its digits is 21600, while the sum is 34.

The square root of 66155641 is about 8133.6118053421. The cubic root of 66155641 is about 404.4414206800.

The spelling of 66155641 in words is "sixty-six million, one hundred fifty-five thousand, six hundred forty-one".