168921021 has 16 divisors (see below), whose sum is σ = 233928000. Its totient is φ = 108332928.

The previous prime is 168920989. The next prime is 168921023. The reversal of 168921021 is 120129861.

It is a happy number.

168921021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 168921021 - 2⁵ = 168920989 is a prime.

It is a super-2 number, since 2×168921021² = 57068622671364882, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 168921021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (168921023) 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, 1330 + ... + 18428.

It is an arithmetic number, because the mean of its divisors is an integer number (14620500).

Almost surely, 2^168921021 is an apocalyptic number.

It is an amenable number.

168921021 is a deficient number, since it is larger than the sum of its proper divisors (65006979).

168921021 is a wasteful number, since it uses less digits than its factorization.

168921021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17228.

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 168921021 is about 12996.9619911732. The cubic root of 168921021 is about 552.7913422861.

The spelling of 168921021 in words is "one hundred sixty-eight million, nine hundred twenty-one thousand, twenty-one".