121816229887521 has 27 divisors (see below), whose sum is σ = 190533750778137. Its totient is φ = 74963568888000.

The previous prime is 121816229887493. The next prime is 121816229887529. The reversal of 121816229887521 is 125788922618121.

The square root of 121816229887521 is 11037039.

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

121816229887521 is a `hidden beast` number, since 1 + 2 + 1 + 8 + 1 + 6 + 2 + 29 + 8 + 87 + 521 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 62557580142225 + 59258649745296 = 7909335^2 + 7697964^2 .

It is a de Polignac number, because none of the positive numbers 2^k-121816229887521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121816229887529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 430303021 + ... + 430586021.

Almost surely, 2^{121816229887521} is an apocalyptic number.

121816229887521 is the 11037039-th square number.

121816229887521 is the 5518520-th centered octagonal number.

It is an amenable number.

121816229887521 is a deficient number, since it is larger than the sum of its proper divisors (68717520890616).

121816229887521 is an frugal number, since it uses more digits than its factorization.

121816229887521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 566034 (or 283017 counting only the distinct ones).

The product of its digits is 15482880, while the sum is 63.

The spelling of 121816229887521 in words is "one hundred twenty-one trillion, eight hundred sixteen billion, two hundred twenty-nine million, eight hundred eighty-seven thousand, five hundred twenty-one".