999997538090861 has 4 divisors (see below), whose sum is σ = 1007296790193852. Its totient is φ = 992698285987872.

The previous prime is 999997538090753. The next prime is 999997538090923. The reversal of 999997538090861 is 168090835799999.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 814897295516836 + 185100242574025 = 28546406^2 + 13605155^2 .

It is a cyclic number.

It is not a de Polignac number, because 999997538090861 - 2¹⁸ = 999997537828717 is a prime.

It is a super-3 number, since 3×999997538090861³ (a number of 46 digits) contains 333 as substring.

It is a pancake number, because a pancake can be divided into 999997538090861 parts by 44721304 straight cuts.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999997538093861) 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, 3649626051290 + ... + 3649626051563.

It is an arithmetic number, because the mean of its divisors is an integer number (251824197548463).

Almost surely, 2^{999997538090861} is an apocalyptic number.

It is an amenable number.

999997538090861 is a deficient number, since it is larger than the sum of its proper divisors (7299252102991).

999997538090861 is a wasteful number, since it uses less digits than its factorization.

999997538090861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7299252102990.

The product of its (nonzero) digits is 21427701120, while the sum is 92.

The spelling of 999997538090861 in words is "nine hundred ninety-nine trillion, nine hundred ninety-seven billion, five hundred thirty-eight million, ninety thousand, eight hundred sixty-one".