166663987 has 4 divisors (see below), whose sum is σ = 190473136. Its totient is φ = 142854840.

The previous prime is 166663979. The next prime is 166663997. The reversal of 166663987 is 789366661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 789366661 = 17 ⋅46433333.

It is a cyclic number.

It is not a de Polignac number, because 166663987 - 2³ = 166663979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (166663997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11904564 + ... + 11904577.

It is an arithmetic number, because the mean of its divisors is an integer number (47618284).

Almost surely, 2^166663987 is an apocalyptic number.

166663987 is the 7454-th hex number.

166663987 is a deficient number, since it is larger than the sum of its proper divisors (23809149).

166663987 is an equidigital number, since it uses as much as digits as its factorization.

166663987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23809148.

The product of its digits is 1959552, while the sum is 52.

The square root of 166663987 is about 12909.8407038972. The cubic root of 166663987 is about 550.3182587785.

The spelling of 166663987 in words is "one hundred sixty-six million, six hundred sixty-three thousand, nine hundred eighty-seven".