99780121 has 9 divisors (see below), whose sum is σ = 116152149. Its totient is φ = 85465884.

The previous prime is 99780091. The next prime is 99780137. The reversal of 99780121 is 12108799.

The square root of 99780121 is 9989.

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

It is not a de Polignac number, because 99780121 - 2¹⁵ = 99747353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (99780521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 69210 + ... + 70636.

Almost surely, 2^99780121 is an apocalyptic number.

99780121 is the 9989-th square number.

99780121 is the 4995-th centered octagonal number.

It is an amenable number.

99780121 is a deficient number, since it is larger than the sum of its proper divisors (16372028).

99780121 is an frugal number, since it uses more digits than its factorization.

99780121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2868 (or 1434 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 37.

The cubic root of 99780121 is about 463.8184377460.

It can be divided in two parts, 997 and 80121, that added together give a palindrome (81118).

The spelling of 99780121 in words is "ninety-nine million, seven hundred eighty thousand, one hundred twenty-one".