915728121 has 81 divisors (see below), whose sum is σ = 1704277029. Its totient is φ = 472071600.

The previous prime is 915728111. The next prime is 915728131. The reversal of 915728121 is 121827519.

It is a happy number.

The square root of 915728121 is 30261.

It is a perfect power (a square), and thus also a powerful number.

915728121 is a `hidden beast` number, since 9 + 1 + 572 + 81 + 2 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (915728111) and next prime (915728131).

It is not a de Polignac number, because 915728121 - 2⁵ = 915728089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (915728111) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 6990226 + ... + 6990356.

Almost surely, 2^915728121 is an apocalyptic number.

915728121 is the 30261-st square number.

915728121 is the 15131-st centered octagonal number.

It is an amenable number.

915728121 is a deficient number, since it is larger than the sum of its proper divisors (788548908).

915728121 is a wasteful number, since it uses less digits than its factorization.

915728121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304 (or 152 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The cubic root of 915728121 is about 971.0811345086.

Multiplying 915728121 by its sum of digits (36), we get a square (32966212356 = 181566²).

It can be divided in two parts, 915728 and 121, that added together give a square (915849 = 957²).

The spelling of 915728121 in words is "nine hundred fifteen million, seven hundred twenty-eight thousand, one hundred twenty-one".