666638091518 has 16 divisors (see below), whose sum is σ = 1143310986720. Its totient is φ = 285576331776.

The previous prime is 666638091463. The next prime is 666638091563. The reversal of 666638091518 is 815190836666.

It is a super-2 number, since 2×666638091518² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10442663 + ... + 10506306.

It is an arithmetic number, because the mean of its divisors is an integer number (71456936670).

Almost surely, 2^666638091518 is an apocalyptic number.

666638091518 is a deficient number, since it is larger than the sum of its proper divisors (476672895202).

666638091518 is a wasteful number, since it uses less digits than its factorization.

666638091518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20951251.

The product of its (nonzero) digits is 11197440, while the sum is 59.

The spelling of 666638091518 in words is "six hundred sixty-six billion, six hundred thirty-eight million, ninety-one thousand, five hundred eighteen".