921678785161 has 4 divisors (see below), whose sum is σ = 921722556112. Its totient is φ = 921635014212.

The previous prime is 921678785119. The next prime is 921678785197. The reversal of 921678785161 is 161587876129.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 161587876129 = 3847 ⋅42003607.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-921678785161 is a prime.

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 921678785161.

It is not an unprimeable number, because it can be changed into a prime (921678782161) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21853875 + ... + 21896008.

It is an arithmetic number, because the mean of its divisors is an integer number (230430639028).

Almost surely, 2^921678785161 is an apocalyptic number.

It is an amenable number.

921678785161 is a deficient number, since it is larger than the sum of its proper divisors (43770951).

921678785161 is a wasteful number, since it uses less digits than its factorization.

921678785161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43770950.

The product of its digits is 10160640, while the sum is 61.

The spelling of 921678785161 in words is "nine hundred twenty-one billion, six hundred seventy-eight million, seven hundred eighty-five thousand, one hundred sixty-one".