168719981 has 4 divisors (see below), whose sum is σ = 177600000. Its totient is φ = 159839964.

The previous prime is 168719977. The next prime is 168719983. The reversal of 168719981 is 189917861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 168719981 - 2² = 168719977 is a prime.

It is a super-2 number, since 2×168719981² = 56932863977280722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168719983) 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, 4439981 + ... + 4440018.

It is an arithmetic number, because the mean of its divisors is an integer number (44400000).

Almost surely, 2^168719981 is an apocalyptic number.

It is an amenable number.

168719981 is a deficient number, since it is larger than the sum of its proper divisors (8880019).

168719981 is an equidigital number, since it uses as much as digits as its factorization.

168719981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8880018.

The product of its digits is 217728, while the sum is 50.

The square root of 168719981 is about 12989.2255735282. The cubic root of 168719981 is about 552.5719551665.

The spelling of 168719981 in words is "one hundred sixty-eight million, seven hundred nineteen thousand, nine hundred eighty-one".