121557128 has 64 divisors (see below), whose sum is σ = 291150720. Its totient is φ = 46195200.

The previous prime is 121557119. The next prime is 121557131. The reversal of 121557128 is 821755121.

It is a super-2 number, since 2×121557128² = 29552270735216768, which contains 22 as substring.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 121557094 and 121557103.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 22850 + ... + 27662.

It is an arithmetic number, because the mean of its divisors is an integer number (4549230).

Almost surely, 2^121557128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 121557128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145575360).

121557128 is an abundant number, since it is smaller than the sum of its proper divisors (169593592).

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

121557128 is a wasteful number, since it uses less digits than its factorization.

121557128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4878 (or 4874 counting only the distinct ones).

The product of its digits is 5600, while the sum is 32.

The square root of 121557128 is about 11025.2949166904. The cubic root of 121557128 is about 495.3667017141.

The spelling of 121557128 in words is "one hundred twenty-one million, five hundred fifty-seven thousand, one hundred twenty-eight".