166861890 has 128 divisors (see below), whose sum is σ = 484081920. Its totient is φ = 40656384.

The previous prime is 166861889. The next prime is 166861927. The reversal of 166861890 is 98168661.

It is a happy number.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 480697 + ... + 481043.

It is an arithmetic number, because the mean of its divisors is an integer number (3781890).

Almost surely, 2^166861890 is an apocalyptic number.

166861890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 166861890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (242040960).

166861890 is an abundant number, since it is smaller than the sum of its proper divisors (317220030).

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

166861890 is a wasteful number, since it uses less digits than its factorization.

166861890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 513 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 166861890 is about 12917.5032417259. The cubic root of 166861890 is about 550.5359953893.

The spelling of 166861890 in words is "one hundred sixty-six million, eight hundred sixty-one thousand, eight hundred ninety".