998128861 has 4 divisors (see below), whose sum is σ = 1041525792. Its totient is φ = 954731932.

The previous prime is 998128847. The next prime is 998128889. The reversal of 998128861 is 168821899.

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: 168821899 = 1171 ⋅144169.

It is a de Polignac number, because none of the positive numbers 2^k-998128861 is a prime.

It is a super-2 number, since 2×998128861² = 1992522446322314642, which contains 22 as substring.

It is a pancake number, because a pancake can be divided into 998128861 parts by 44679 straight cuts.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 998128799 and 998128808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998128891) 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, 21698431 + ... + 21698476.

It is an arithmetic number, because the mean of its divisors is an integer number (260381448).

Almost surely, 2^998128861 is an apocalyptic number.

It is an amenable number.

998128861 is a deficient number, since it is larger than the sum of its proper divisors (43396931).

998128861 is a wasteful number, since it uses less digits than its factorization.

998128861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43396930.

The product of its digits is 497664, while the sum is 52.

The square root of 998128861 is about 31593.1774438723. The cubic root of 998128861 is about 999.3758975772.

The spelling of 998128861 in words is "nine hundred ninety-eight million, one hundred twenty-eight thousand, eight hundred sixty-one".