168690721 has 8 divisors (see below), whose sum is σ = 177780800. Its totient is φ = 159621840.

The previous prime is 168690719. The next prime is 168690727. The reversal of 168690721 is 127096861.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 168690721 - 2¹ = 168690719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (168690727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12631 + ... + 22291.

It is an arithmetic number, because the mean of its divisors is an integer number (22222600).

Almost surely, 2^168690721 is an apocalyptic number.

It is an amenable number.

168690721 is a deficient number, since it is larger than the sum of its proper divisors (9090079).

168690721 is an equidigital number, since it uses as much as digits as its factorization.

168690721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10599.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 168690721 is about 12988.0992065814. The cubic root of 168690721 is about 552.5400103427.

The spelling of 168690721 in words is "one hundred sixty-eight million, six hundred ninety thousand, seven hundred twenty-one".