121761566261 has 4 divisors (see below), whose sum is σ = 121840480032. Its totient is φ = 121682652492.

The previous prime is 121761566221. The next prime is 121761566293. The reversal of 121761566261 is 162665167121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 121761566261 - 2¹⁸ = 121761304117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121761566221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39454571 + ... + 39457656.

It is an arithmetic number, because the mean of its divisors is an integer number (30460120008).

Almost surely, 2^121761566261 is an apocalyptic number.

It is an amenable number.

121761566261 is a deficient number, since it is larger than the sum of its proper divisors (78913771).

121761566261 is an equidigital number, since it uses as much as digits as its factorization.

121761566261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78913770.

The product of its digits is 181440, while the sum is 44.

The spelling of 121761566261 in words is "one hundred twenty-one billion, seven hundred sixty-one million, five hundred sixty-six thousand, two hundred sixty-one".