166077901981 has 4 divisors (see below), whose sum is σ = 173298680352. Its totient is φ = 158857123612.

The previous prime is 166077901973. The next prime is 166077902021. The reversal of 166077901981 is 189109770661.

166077901981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 166077901981 - 2³ = 166077901973 is a prime.

It is a super-3 number, since 3×166077901981³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166077901931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3610389151 + ... + 3610389196.

It is an arithmetic number, because the mean of its divisors is an integer number (43324670088).

Almost surely, 2^166077901981 is an apocalyptic number.

It is an amenable number.

166077901981 is a deficient number, since it is larger than the sum of its proper divisors (7220778371).

166077901981 is an equidigital number, since it uses as much as digits as its factorization.

166077901981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7220778370.

The product of its (nonzero) digits is 1143072, while the sum is 55.

The spelling of 166077901981 in words is "one hundred sixty-six billion, seventy-seven million, nine hundred one thousand, nine hundred eighty-one".