666745537 has 4 divisors (see below), whose sum is σ = 670429396. Its totient is φ = 663061680.

The previous prime is 666745523. The next prime is 666745553. The reversal of 666745537 is 735547666.

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 19501056 + 647244481 = 4416^2 + 25441^2 .

It is a cyclic number.

It is not a de Polignac number, because 666745537 - 2¹⁹ = 666221249 is a prime.

It is a super-2 number, since 2×666745537² = 889099222218836738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666742537) 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, 1841658 + ... + 1842019.

It is an arithmetic number, because the mean of its divisors is an integer number (167607349).

Almost surely, 2^666745537 is an apocalyptic number.

It is an amenable number.

666745537 is a deficient number, since it is larger than the sum of its proper divisors (3683859).

666745537 is a wasteful number, since it uses less digits than its factorization.

666745537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3683858.

The product of its digits is 3175200, while the sum is 49.

The square root of 666745537 is about 25821.4162469838. The cubic root of 666745537 is about 873.6149131691.

The spelling of 666745537 in words is "six hundred sixty-six million, seven hundred forty-five thousand, five hundred thirty-seven".