121781456784 has 135 divisors (see below), whose sum is σ = 369217509843. Its totient is φ = 37454466816.

The previous prime is 121781456777. The next prime is 121781456789. The reversal of 121781456784 is 487654187121.

It is a happy number.

The square root of 121781456784 is 348972.

It is a perfect power (a square), and thus also a powerful number.

121781456784 is a `hidden beast` number, since 1 + 2 + 1 + 78 + 1 + 4 + 567 + 8 + 4 = 666.

121781456784 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 677456784 + 121104000000 = 26028^2 + 348000^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 121781456784.

It is not an unprimeable number, because it can be changed into a prime (121781456789) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 54438514 + ... + 54440750.

Almost surely, 2^121781456784 is an apocalyptic number.

121781456784 is the 348972-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121781456784

121781456784 is an abundant number, since it is smaller than the sum of its proper divisors (247436053059).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

121781456784 is an equidigital number, since it uses as much as digits as its factorization.

121781456784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4514 (or 2255 counting only the distinct ones).

The product of its digits is 3010560, while the sum is 54.

The spelling of 121781456784 in words is "one hundred twenty-one billion, seven hundred eighty-one million, four hundred fifty-six thousand, seven hundred eighty-four".