166521986 has 4 divisors (see below), whose sum is σ = 249782982. Its totient is φ = 83260992.

The previous prime is 166521983. The next prime is 166522003. The reversal of 166521986 is 689125661.

166521986 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.

It can be written as a sum of positive squares in only one way, i.e., 118483225 + 48038761 = 10885^2 + 6931^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (166521983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41630495 + ... + 41630498.

Almost surely, 2^166521986 is an apocalyptic number.

166521986 is a deficient number, since it is larger than the sum of its proper divisors (83260996).

166521986 is an equidigital number, since it uses as much as digits as its factorization.

166521986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83260995.

The product of its digits is 155520, while the sum is 44.

The square root of 166521986 is about 12904.3398126367. The cubic root of 166521986 is about 550.1619203699.

The spelling of 166521986 in words is "one hundred sixty-six million, five hundred twenty-one thousand, nine hundred eighty-six".