99999666555 has 32 divisors (see below), whose sum is σ = 168723129600. Its totient is φ = 50435356032.

The previous prime is 99999666553. The next prime is 99999666583. The reversal of 99999666555 is 55566699999.

It is not a de Polignac number, because 99999666555 - 2¹ = 99999666553 is a prime.

It is a super-2 number, since 2×99999666555² (a number of 23 digits) contains 22 as substring.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (99999666553) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 156225 + ... + 473714.

It is an arithmetic number, because the mean of its divisors is an integer number (5272597800).

Almost surely, 2^99999666555 is an apocalyptic number.

99999666555 is a gapful number since it is divisible by the number (95) formed by its first and last digit.

99999666555 is a deficient number, since it is larger than the sum of its proper divisors (68723463045).

99999666555 is a wasteful number, since it uses less digits than its factorization.

99999666555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 630523.

The product of its digits is 1594323000, while the sum is 78.

The spelling of 99999666555 in words is "ninety-nine billion, nine hundred ninety-nine million, six hundred sixty-six thousand, five hundred fifty-five".