991778243163 has 32 divisors (see below), whose sum is σ = 1398967532544. Its totient is φ = 623685629952.

The previous prime is 991778243089. The next prime is 991778243167. The reversal of 991778243163 is 361342877199.

It is not a de Polignac number, because 991778243163 - 2²⁵ = 991744688731 is a prime.

It is a super-2 number, since 2×991778243163² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 991778243097 and 991778243106.

It is not an unprimeable number, because it can be changed into a prime (991778243167) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 65790795 + ... + 65805867.

It is an arithmetic number, because the mean of its divisors is an integer number (43717735392).

Almost surely, 2^991778243163 is an apocalyptic number.

991778243163 is a deficient number, since it is larger than the sum of its proper divisors (407189289381).

991778243163 is a wasteful number, since it uses less digits than its factorization.

991778243163 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28235.

The product of its digits is 13716864, while the sum is 60.

The spelling of 991778243163 in words is "nine hundred ninety-one billion, seven hundred seventy-eight million, two hundred forty-three thousand, one hundred sixty-three".