121672720661 has 8 divisors (see below), whose sum is σ = 123399080064. Its totient is φ = 119946713040.

The previous prime is 121672720613. The next prime is 121672720699. The reversal of 121672720661 is 166027276121.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121672720661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121672720361) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 652616 + ... + 818078.

It is an arithmetic number, because the mean of its divisors is an integer number (15424885008).

Almost surely, 2^121672720661 is an apocalyptic number.

It is an amenable number.

121672720661 is a deficient number, since it is larger than the sum of its proper divisors (1726359403).

121672720661 is a wasteful number, since it uses less digits than its factorization.

121672720661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175891.

The product of its (nonzero) digits is 84672, while the sum is 41.

Adding to 121672720661 its reverse (166027276121), we get a palindrome (287699996782).

The spelling of 121672720661 in words is "one hundred twenty-one billion, six hundred seventy-two million, seven hundred twenty thousand, six hundred sixty-one".