166681890 has 96 divisors (see below), whose sum is σ = 446440176. Its totient is φ = 43130880.

The previous prime is 166681877. The next prime is 166681901. The reversal of 166681890 is 98186661.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 194481 + 166487409 = 441^2 + 12903^2 .

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 532374 + ... + 532686.

Almost surely, 2^166681890 is an apocalyptic number.

166681890 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 166681890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (223220088).

166681890 is an abundant number, since it is smaller than the sum of its proper divisors (279758286).

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

166681890 is a wasteful number, since it uses less digits than its factorization.

166681890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 481 counting only the distinct ones).

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

The square root of 166681890 is about 12910.5340710600. The cubic root of 166681890 is about 550.3379630854.

The spelling of 166681890 in words is "one hundred sixty-six million, six hundred eighty-one thousand, eight hundred ninety".