998978261121 has 27 divisors (see below), whose sum is σ = 1448197796227. Its totient is φ = 663580736880.

The previous prime is 998978261101. The next prime is 998978261129. The reversal of 998978261121 is 121162879899.

The square root of 998978261121 is 999489.

It is a perfect power (a square), and thus also a powerful number.

998978261121 is a `hidden beast` number, since 9 + 9 + 8 + 9 + 7 + 8 + 2 + 611 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 63572058225 + 935406202896 = 252135^2 + 967164^2 .

It is not a de Polignac number, because 998978261121 - 2⁵ = 998978261089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (998978261129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1292338891 + ... + 1292339663.

Almost surely, 2^998978261121 is an apocalyptic number.

998978261121 is the 999489-th square number.

998978261121 is the 499745-th centered octagonal number.

It is an amenable number.

998978261121 is a deficient number, since it is larger than the sum of its proper divisors (449219535106).

998978261121 is an frugal number, since it uses more digits than its factorization.

998978261121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2414 (or 1207 counting only the distinct ones).

The product of its digits is 7838208, while the sum is 63.

The spelling of 998978261121 in words is "nine hundred ninety-eight billion, nine hundred seventy-eight million, two hundred sixty-one thousand, one hundred twenty-one".