166541778 has 64 divisors (see below), whose sum is σ = 405417600. Its totient is φ = 50362560.

The previous prime is 166541777. The next prime is 166541797. The reversal of 166541778 is 877145661.

166541778 is a `hidden beast` number, since 166 + 5 + 417 + 78 = 666.

It is not an unprimeable number, because it can be changed into a prime (166541777) 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, 39408 + ... + 43428.

It is an arithmetic number, because the mean of its divisors is an integer number (6334650).

Almost surely, 2^166541778 is an apocalyptic number.

166541778 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 166541778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (202708800).

166541778 is an abundant number, since it is smaller than the sum of its proper divisors (238875822).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

166541778 is a wasteful number, since it uses less digits than its factorization.

166541778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4104 (or 4098 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 166541778 is about 12905.1066636429. The cubic root of 166541778 is about 550.1837160371.

The spelling of 166541778 in words is "one hundred sixty-six million, five hundred forty-one thousand, seven hundred seventy-eight".