10198778121 has 75 divisors (see below), whose sum is σ = 17851307991. Its totient is φ = 5802423984.

The previous prime is 10198778111. The next prime is 10198778129. The reversal of 10198778121 is 12187789101.

The square root of 10198778121 is 100989.

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

It can be written as a sum of positive squares in only one way, i.e., 9498646521 + 700131600 = 97461^2 + 26460^2 .

It is not a de Polignac number, because 10198778121 - 2⁹ = 10198777609 is a prime.

It is a super-2 number, since 2×10198778121² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (10198778129) by changing a digit.

It is a polite number, since it can be written in 74 ways as a sum of consecutive naturals, for example, 44536035 + ... + 44536263.

Almost surely, 2^10198778121 is an apocalyptic number.

10198778121 is the 100989-th square number.

10198778121 is the 50495-th centered octagonal number.

It is an amenable number.

10198778121 is a deficient number, since it is larger than the sum of its proper divisors (7652529870).

10198778121 is an frugal number, since it uses more digits than its factorization.

10198778121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 498 (or 239 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 45.

The spelling of 10198778121 in words is "ten billion, one hundred ninety-eight million, seven hundred seventy-eight thousand, one hundred twenty-one".