66780157 has 4 divisors (see below), whose sum is σ = 66800700. Its totient is φ = 66759616.

The previous prime is 66780151. The next prime is 66780209. The reversal of 66780157 is 75108766.

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 7474756 + 59305401 = 2734^2 + 7701^2 .

It is a cyclic number.

It is not a de Polignac number, because 66780157 - 2³ = 66780149 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66780151) 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, 4198 + ... + 12295.

It is an arithmetic number, because the mean of its divisors is an integer number (16700175).

Almost surely, 2^66780157 is an apocalyptic number.

It is an amenable number.

66780157 is a deficient number, since it is larger than the sum of its proper divisors (20543).

66780157 is a wasteful number, since it uses less digits than its factorization.

66780157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20542.

The product of its (nonzero) digits is 70560, while the sum is 40.

The square root of 66780157 is about 8171.9126892056. The cubic root of 66780157 is about 405.7100929737.

The spelling of 66780157 in words is "sixty-six million, seven hundred eighty thousand, one hundred fifty-seven".