166406621555 has 4 divisors (see below), whose sum is σ = 199687945872. Its totient is φ = 133125297240.

The previous prime is 166406621519. The next prime is 166406621561. The reversal of 166406621555 is 555126604661.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 166406621555 - 2¹² = 166406617459 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16640662151 + ... + 16640662160.

It is an arithmetic number, because the mean of its divisors is an integer number (49921986468).

Almost surely, 2^166406621555 is an apocalyptic number.

166406621555 is a deficient number, since it is larger than the sum of its proper divisors (33281324317).

166406621555 is an equidigital number, since it uses as much as digits as its factorization.

166406621555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33281324316.

The product of its (nonzero) digits is 1296000, while the sum is 47.

The spelling of 166406621555 in words is "one hundred sixty-six billion, four hundred six million, six hundred twenty-one thousand, five hundred fifty-five".