121751781919 has 4 divisors (see below), whose sum is σ = 121769871496. Its totient is φ = 121733692344.

The previous prime is 121751781889. The next prime is 121751781971. The reversal of 121751781919 is 919187157121.

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

It is a cyclic number.

It is not a de Polignac number, because 121751781919 - 2¹³ = 121751773727 is a prime.

It is a super-2 number, since 2×121751781919² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121751781979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9034689 + ... + 9048154.

It is an arithmetic number, because the mean of its divisors is an integer number (30442467874).

Almost surely, 2^121751781919 is an apocalyptic number.

121751781919 is a deficient number, since it is larger than the sum of its proper divisors (18089577).

121751781919 is an equidigital number, since it uses as much as digits as its factorization.

121751781919 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18089576.

The product of its digits is 317520, while the sum is 52.

The spelling of 121751781919 in words is "one hundred twenty-one billion, seven hundred fifty-one million, seven hundred eighty-one thousand, nine hundred nineteen".