121721128 has 32 divisors (see below), whose sum is σ = 241355520. Its totient is φ = 57456000.

The previous prime is 121721113. The next prime is 121721141. The reversal of 121721128 is 821127121.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4183 + ... + 16153.

It is an arithmetic number, because the mean of its divisors is an integer number (7542360).

Almost surely, 2^121721128 is an apocalyptic number.

It is an amenable number.

121721128 is a deficient number, since it is larger than the sum of its proper divisors (119634392).

121721128 is a wasteful number, since it uses less digits than its factorization.

121721128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12049 (or 12045 counting only the distinct ones).

The product of its digits is 448, while the sum is 25.

The square root of 121721128 is about 11032.7298525796. The cubic root of 121721128 is about 495.5893778952.

Adding to 121721128 its reverse (821127121), we get a palindrome (942848249).

The spelling of 121721128 in words is "one hundred twenty-one million, seven hundred twenty-one thousand, one hundred twenty-eight".