66142409 has 4 divisors (see below), whose sum is σ = 66426516. Its totient is φ = 65858304.

The previous prime is 66142343. The next prime is 66142423. The reversal of 66142409 is 90424166.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24255625 + 41886784 = 4925^2 + 6472^2 .

It is a cyclic number.

It is not a de Polignac number, because 66142409 - 2²⁴ = 49365193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66142429) 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, 141704 + ... + 142169.

It is an arithmetic number, because the mean of its divisors is an integer number (16606629).

Almost surely, 2^66142409 is an apocalyptic number.

It is an amenable number.

66142409 is a deficient number, since it is larger than the sum of its proper divisors (284107).

66142409 is a wasteful number, since it uses less digits than its factorization.

66142409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284106.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 66142409 is about 8132.7983498916. The cubic root of 66142409 is about 404.4144543440.

The spelling of 66142409 in words is "sixty-six million, one hundred forty-two thousand, four hundred nine".