168893761921 has 16 divisors (see below), whose sum is σ = 172157896144. Its totient is φ = 165657913344.

The previous prime is 168893761913. The next prime is 168893761931. The reversal of 168893761921 is 129167398861.

It can be written as a sum of positive squares in 8 ways, for example, as 13745217600 + 155148544321 = 117240^2 + 393889^2 .

It is a cyclic number.

It is not a de Polignac number, because 168893761921 - 2³ = 168893761913 is a prime.

It is a super-2 number, since 2×168893761921² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 168893761921.

It is not an unprimeable number, because it can be changed into a prime (168893761901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9757951 + ... + 9775243.

It is an arithmetic number, because the mean of its divisors is an integer number (10759868509).

Almost surely, 2^168893761921 is an apocalyptic number.

It is an amenable number.

168893761921 is a deficient number, since it is larger than the sum of its proper divisors (3264134223).

168893761921 is a wasteful number, since it uses less digits than its factorization.

168893761921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18100.

The product of its digits is 7838208, while the sum is 61.

The spelling of 168893761921 in words is "one hundred sixty-eight billion, eight hundred ninety-three million, seven hundred sixty-one thousand, nine hundred twenty-one".