121720550139 has 6 divisors (see below), whose sum is σ = 175818572436. Its totient is φ = 81147033420.

The previous prime is 121720550123. The next prime is 121720550173. The reversal of 121720550139 is 931055027121.

121720550139 is a `hidden beast` number, since 1 + 2 + 1 + 72 + 0 + 550 + 1 + 39 = 666.

It is not a de Polignac number, because 121720550139 - 2⁴ = 121720550123 is a prime.

It is a super-2 number, since 2×121720550139² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (121720554139) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6762252777 + ... + 6762252794.

It is an arithmetic number, because the mean of its divisors is an integer number (29303095406).

Almost surely, 2^121720550139 is an apocalyptic number.

121720550139 is a deficient number, since it is larger than the sum of its proper divisors (54098022297).

121720550139 is a wasteful number, since it uses less digits than its factorization.

121720550139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13524505577 (or 13524505574 counting only the distinct ones).

The product of its (nonzero) digits is 18900, while the sum is 36.

The spelling of 121720550139 in words is "one hundred twenty-one billion, seven hundred twenty million, five hundred fifty thousand, one hundred thirty-nine".