121665591450 has 432 divisors, whose sum is σ = 369306972216. Its totient is φ = 28527206400.

The previous prime is 121665591431. The next prime is 121665591479. The reversal of 121665591450 is 54195566121.

121665591450 is a `hidden beast` number, since 1 + 2 + 1 + 6 + 6 + 5 + 591 + 4 + 50 = 666.

It can be written as a sum of positive squares in 12 ways, for example, as 33529638321 + 88135953129 = 183111^2 + 296877^2 .

It is a super-2 number, since 2×121665591450² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 121665591396 and 121665591405.

It is an unprimeable number.

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 215 ways as a sum of consecutive naturals, for example, 1076686594 + ... + 1076686706.

Almost surely, 2^121665591450 is an apocalyptic number.

121665591450 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 121665591450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184653486108).

121665591450 is an abundant number, since it is smaller than the sum of its proper divisors (247641380766).

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

121665591450 is a wasteful number, since it uses less digits than its factorization.

121665591450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319 (or 244 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The spelling of 121665591450 in words is "one hundred twenty-one billion, six hundred sixty-five million, five hundred ninety-one thousand, four hundred fifty".