66728537 has 4 divisors (see below), whose sum is σ = 67987620. Its totient is φ = 65469456.

The previous prime is 66728521. The next prime is 66728567. The reversal of 66728537 is 73582766.

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 36048016 + 30680521 = 6004^2 + 5539^2 .

It is a cyclic number.

It is not a de Polignac number, because 66728537 - 2⁴ = 66728521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66728567) 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, 629462 + ... + 629567.

It is an arithmetic number, because the mean of its divisors is an integer number (16996905).

Almost surely, 2^66728537 is an apocalyptic number.

It is an amenable number.

66728537 is a deficient number, since it is larger than the sum of its proper divisors (1259083).

66728537 is a wasteful number, since it uses less digits than its factorization.

66728537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1259082.

The product of its digits is 423360, while the sum is 44.

The square root of 66728537 is about 8168.7536993106. The cubic root of 66728537 is about 405.6055302094.

The spelling of 66728537 in words is "sixty-six million, seven hundred twenty-eight thousand, five hundred thirty-seven".