666556115501 has 2 divisors, whose sum is σ = 666556115502. Its totient is φ = 666556115500.

The previous prime is 666556115431. The next prime is 666556115527. The reversal of 666556115501 is 105511655666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 487141182025 + 179414933476 = 697955^2 + 423574^2 .

It is a cyclic number.

It is not a de Polignac number, because 666556115501 - 2³⁴ = 649376246317 is a prime.

It is a super-2 number, since 2×666556115501² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666556115591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333278057750 + 333278057751.

It is an arithmetic number, because the mean of its divisors is an integer number (333278057751).

Almost surely, 2^666556115501 is an apocalyptic number.

It is an amenable number.

666556115501 is a deficient number, since it is larger than the sum of its proper divisors (1).

666556115501 is an equidigital number, since it uses as much as digits as its factorization.

666556115501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 810000, while the sum is 47.

The spelling of 666556115501 in words is "six hundred sixty-six billion, five hundred fifty-six million, one hundred fifteen thousand, five hundred one".