121573729728 has 504 divisors, whose sum is σ = 403154388000. Its totient is φ = 34933493760.

The previous prime is 121573729699. The next prime is 121573729729. The reversal of 121573729728 is 827927375121.

121573729728 is a `hidden beast` number, since 1 + 21 + 573 + 7 + 29 + 7 + 28 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121573729729) 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 71 ways as a sum of consecutive naturals, for example, 238847938 + ... + 238848446.

It is an arithmetic number, because the mean of its divisors is an integer number (799909500).

Almost surely, 2^121573729728 is an apocalyptic number.

121573729728 is a gapful number since it is divisible by the number (18) 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 121573729728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (201577194000).

121573729728 is an abundant number, since it is smaller than the sum of its proper divisors (281580658272).

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

121573729728 is a wasteful number, since it uses less digits than its factorization.

121573729728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 721 (or 697 counting only the distinct ones).

The product of its digits is 2963520, while the sum is 54.

The spelling of 121573729728 in words is "one hundred twenty-one billion, five hundred seventy-three million, seven hundred twenty-nine thousand, seven hundred twenty-eight".