128121645 has 16 divisors (see below), whose sum is σ = 205414272. Its totient is φ = 68191680.

The previous prime is 128121629. The next prime is 128121649. The reversal of 128121645 is 546121821.

It is not a de Polignac number, because 128121645 - 2⁴ = 128121629 is a prime.

It is a super-3 number, since 3×128121645³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128121649) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 946 + ... + 16035.

It is an arithmetic number, because the mean of its divisors is an integer number (12838392).

Almost surely, 2^128121645 is an apocalyptic number.

128121645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128121645 is a deficient number, since it is larger than the sum of its proper divisors (77292627).

128121645 is a wasteful number, since it uses less digits than its factorization.

128121645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17492.

The product of its digits is 3840, while the sum is 30.

The square root of 128121645 is about 11319.0832225936. The cubic root of 128121645 is about 504.1280184688.

The spelling of 128121645 in words is "one hundred twenty-eight million, one hundred twenty-one thousand, six hundred forty-five".