121252145521 has 4 divisors (see below), whose sum is σ = 130579233652. Its totient is φ = 111925057392.

The previous prime is 121252145519. The next prime is 121252145611. The reversal of 121252145521 is 125541252121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125541252121 = 22031 ⋅5698391.

It can be written as a sum of positive squares in 2 ways, for example, as 20740320225 + 100511825296 = 144015^2 + 317036^2 .

It is a cyclic number.

It is not a de Polignac number, because 121252145521 - 2¹ = 121252145519 is a prime.

It is a super-2 number, since 2×121252145521² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121252185521) 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 3 ways as a sum of consecutive naturals, for example, 4663544046 + ... + 4663544071.

It is an arithmetic number, because the mean of its divisors is an integer number (32644808413).

Almost surely, 2^121252145521 is an apocalyptic number.

It is an amenable number.

121252145521 is a deficient number, since it is larger than the sum of its proper divisors (9327088131).

121252145521 is an equidigital number, since it uses as much as digits as its factorization.

121252145521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9327088130.

The product of its digits is 8000, while the sum is 31.

Adding to 121252145521 its reverse (125541252121), we get a palindrome (246793397642).

The spelling of 121252145521 in words is "one hundred twenty-one billion, two hundred fifty-two million, one hundred forty-five thousand, five hundred twenty-one".