121991400 has 384 divisors, whose sum is σ = 468720000. Its totient is φ = 29030400.

The previous prime is 121991377. The next prime is 121991407. The reversal of 121991400 is 4199121.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (121991407) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2975380 + ... + 2975420.

It is an arithmetic number, because the mean of its divisors is an integer number (1220625).

Almost surely, 2^121991400 is an apocalyptic number.

121991400 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 121991400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (234360000).

121991400 is an abundant number, since it is smaller than the sum of its proper divisors (346728600).

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

121991400 is a wasteful number, since it uses less digits than its factorization.

121991400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 121991400 is about 11044.9717066184. The cubic root of 121991400 is about 495.9559122277.

The spelling of 121991400 in words is "one hundred twenty-one million, nine hundred ninety-one thousand, four hundred".