166221778090 has 32 divisors (see below), whose sum is σ = 312484884480. Its totient is φ = 63541467264.

The previous prime is 166221778057. The next prime is 166221778091. The reversal of 166221778090 is 90877122661.

166221778090 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×166221778090² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166221778091) 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 15 ways as a sum of consecutive naturals, for example, 60394 + ... + 579733.

It is an arithmetic number, because the mean of its divisors is an integer number (9765152640).

Almost surely, 2^166221778090 is an apocalyptic number.

166221778090 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

166221778090 is a deficient number, since it is larger than the sum of its proper divisors (146263106390).

166221778090 is a wasteful number, since it uses less digits than its factorization.

166221778090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641286.

The product of its (nonzero) digits is 508032, while the sum is 49.

The spelling of 166221778090 in words is "one hundred sixty-six billion, two hundred twenty-one million, seven hundred seventy-eight thousand, ninety".