121561751661 has 32 divisors (see below), whose sum is σ = 189473134848. Its totient is φ = 67889802240.

The previous prime is 121561751657. The next prime is 121561751671. The reversal of 121561751661 is 166157165121.

It is not a de Polignac number, because 121561751661 - 2² = 121561751657 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121561751621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 101100 + ... + 503333.

It is an arithmetic number, because the mean of its divisors is an integer number (5921035464).

Almost surely, 2^121561751661 is an apocalyptic number.

It is an amenable number.

121561751661 is a deficient number, since it is larger than the sum of its proper divisors (67911383187).

121561751661 is a wasteful number, since it uses less digits than its factorization.

121561751661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 604661.

The product of its digits is 75600, while the sum is 42.

The spelling of 121561751661 in words is "one hundred twenty-one billion, five hundred sixty-one million, seven hundred fifty-one thousand, six hundred sixty-one".