666610556515 has 16 divisors (see below), whose sum is σ = 803200196448. Its totient is φ = 531110895616.

The previous prime is 666610556473. The next prime is 666610556539. The reversal of 666610556515 is 515655016666.

It is a cyclic number.

It is not a de Polignac number, because 666610556515 - 2³⁷ = 529171603043 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6998349 + ... + 7092961.

It is an arithmetic number, because the mean of its divisors is an integer number (50200012278).

Almost surely, 2^666610556515 is an apocalyptic number.

666610556515 is a deficient number, since it is larger than the sum of its proper divisors (136589639933).

666610556515 is a wasteful number, since it uses less digits than its factorization.

666610556515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100358.

The product of its (nonzero) digits is 4860000, while the sum is 52.

The spelling of 666610556515 in words is "six hundred sixty-six billion, six hundred ten million, five hundred fifty-six thousand, five hundred fifteen".