168638921785 has 8 divisors (see below), whose sum is σ = 202369157640. Its totient is φ = 134909503104.

The previous prime is 168638921779. The next prime is 168638921791. The reversal of 168638921785 is 587129836861.

It is an interprime number because it is at equal distance from previous prime (168638921779) and next prime (168638921791).

It can be written as a sum of positive squares in 4 ways, for example, as 94856608144 + 73782313641 = 307988^2 + 271629^2 .

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 168638921785 - 2¹⁵ = 168638889017 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 427159 + ... + 720931.

It is an arithmetic number, because the mean of its divisors is an integer number (25296144705).

Almost surely, 2^168638921785 is an apocalyptic number.

It is an amenable number.

168638921785 is a deficient number, since it is larger than the sum of its proper divisors (33730235855).

168638921785 is a wasteful number, since it uses less digits than its factorization.

168638921785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408587.

The product of its digits is 34836480, while the sum is 64.

The spelling of 168638921785 in words is "one hundred sixty-eight billion, six hundred thirty-eight million, nine hundred twenty-one thousand, seven hundred eighty-five".