168721840 has 80 divisors (see below), whose sum is σ = 462827520. Its totient is φ = 55975680.

The previous prime is 168721831. The next prime is 168721849. The reversal of 168721840 is 48127861.

168721840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (168721831) and next prime (168721849).

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 168721840.

It is not an unprimeable number, because it can be changed into a prime (168721849) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12501 + ... + 22219.

It is an arithmetic number, because the mean of its divisors is an integer number (5785344).

Almost surely, 2^168721840 is an apocalyptic number.

168721840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 168721840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (231413760).

168721840 is an abundant number, since it is smaller than the sum of its proper divisors (294105680).

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

168721840 is a wasteful number, since it uses less digits than its factorization.

168721840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9770 (or 9764 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 37.

The square root of 168721840 is about 12989.2971326396. The cubic root of 168721840 is about 552.5739846188.

The spelling of 168721840 in words is "one hundred sixty-eight million, seven hundred twenty-one thousand, eight hundred forty".