166851868643 has 4 divisors (see below), whose sum is σ = 175633545960. Its totient is φ = 158070191328.

The previous prime is 166851868639. The next prime is 166851868657. The reversal of 166851868643 is 346868158661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 346868158661 = 17 ⋅20404009333.

It is a cyclic number.

It is not a de Polignac number, because 166851868643 - 2² = 166851868639 is a prime.

It is a super-2 number, since 2×166851868643² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166851868343) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4390838630 + ... + 4390838667.

It is an arithmetic number, because the mean of its divisors is an integer number (43908386490).

Almost surely, 2^166851868643 is an apocalyptic number.

166851868643 is a deficient number, since it is larger than the sum of its proper divisors (8781677317).

166851868643 is an equidigital number, since it uses as much as digits as its factorization.

166851868643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8781677316.

The product of its digits is 39813120, while the sum is 62.

The spelling of 166851868643 in words is "one hundred sixty-six billion, eight hundred fifty-one million, eight hundred sixty-eight thousand, six hundred forty-three".