991803161 has 8 divisors (see below), whose sum is σ = 1051029000. Its totient is φ = 934245760.

The previous prime is 991803149. The next prime is 991803191. The reversal of 991803161 is 161308199.

It can be written as a sum of positive squares in 4 ways, for example, as 95160025 + 896643136 = 9755^2 + 29944^2 .

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 991803161 - 2²⁶ = 924694297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991803121) 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, 415886 + ... + 418263.

It is an arithmetic number, because the mean of its divisors is an integer number (131378625).

Almost surely, 2^991803161 is an apocalyptic number.

It is an amenable number.

991803161 is a deficient number, since it is larger than the sum of its proper divisors (59225839).

991803161 is a wasteful number, since it uses less digits than its factorization.

991803161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 834219.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 991803161 is about 31492.9065187702. The cubic root of 991803161 is about 997.2602207985.

The spelling of 991803161 in words is "nine hundred ninety-one million, eight hundred three thousand, one hundred sixty-one".