661461115121 has 4 divisors (see below), whose sum is σ = 661706740212. Its totient is φ = 661215490032.

The previous prime is 661461115111. The next prime is 661461115127. The reversal of 661461115121 is 121511164166.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 80914647025 + 580546468096 = 284455^2 + 761936^2 .

It is a cyclic number.

It is not a de Polignac number, because 661461115121 - 2³⁸ = 386583208177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661461115127) 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, 122808506 + ... + 122813891.

It is an arithmetic number, because the mean of its divisors is an integer number (165426685053).

Almost surely, 2^661461115121 is an apocalyptic number.

It is an amenable number.

661461115121 is a deficient number, since it is larger than the sum of its proper divisors (245625091).

661461115121 is a wasteful number, since it uses less digits than its factorization.

661461115121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245625090.

The product of its digits is 8640, while the sum is 35.

Adding to 661461115121 its reverse (121511164166), we get a palindrome (782972279287).

The spelling of 661461115121 in words is "six hundred sixty-one billion, four hundred sixty-one million, one hundred fifteen thousand, one hundred twenty-one".