121661440 has 72 divisors (see below), whose sum is σ = 294618870. Its totient is φ = 48218112.

The previous prime is 121661431. The next prime is 121661443. The reversal of 121661440 is 44166121.

It can be written as a sum of positive squares in 3 ways, for example, as 113550336 + 8111104 = 10656^2 + 2848^2 .

It is not an unprimeable number, because it can be changed into a prime (121661443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1116106 + ... + 1116214.

Almost surely, 2^121661440 is an apocalyptic number.

121661440 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 121661440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147309435).

121661440 is an abundant number, since it is smaller than the sum of its proper divisors (172957430).

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

121661440 is an frugal number, since it uses more digits than its factorization.

121661440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 25.

The square root of 121661440 is about 11030.0244786673. The cubic root of 121661440 is about 495.5083577915.

The spelling of 121661440 in words is "one hundred twenty-one million, six hundred sixty-one thousand, four hundred forty".