121851378155520 has 3360 divisors, whose sum is σ = 501368544359424. Its totient is φ = 28206799257600.

The previous prime is 121851378155513. The next prime is 121851378155557. The reversal of 121851378155520 is 25551873158121.

121851378155520 is a `hidden beast` number, since 1 + 2 + 1 + 8 + 5 + 1 + 3 + 7 + 81 + 5 + 552 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 1468088893399 + ... + 1468088893481.

Almost surely, 2^{121851378155520} is an apocalyptic number.

121851378155520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121851378155520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (250684272179712).

121851378155520 is an abundant number, since it is smaller than the sum of its proper divisors (379517166203904).

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

121851378155520 is an frugal number, since it uses more digits than its factorization.

121851378155520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 239 (or 198 counting only the distinct ones).

The product of its (nonzero) digits is 3360000, while the sum is 54.

The spelling of 121851378155520 in words is "one hundred twenty-one trillion, eight hundred fifty-one billion, three hundred seventy-eight million, one hundred fifty-five thousand, five hundred twenty".