915921 has 8 divisors (see below), whose sum is σ = 1356960. Its totient is φ = 610596.

The previous prime is 915919. The next prime is 915947. The reversal of 915921 is 129519.

It is a happy number.

It is not a de Polignac number, because 915921 - 2¹ = 915919 is a prime.

It is a super-3 number, since 3×915921³ = 2305129370633324883, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 33923 = 915921 / (9 + 1 + 5 + 9 + 2 + 1).

It is not an unprimeable number, because it can be changed into a prime (915911) 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 7 ways as a sum of consecutive naturals, for example, 16935 + ... + 16988.

It is an arithmetic number, because the mean of its divisors is an integer number (169620).

2⁹¹⁵⁹²¹ is an apocalyptic number.

It is an amenable number.

915921 is a deficient number, since it is larger than the sum of its proper divisors (441039).

915921 is a wasteful number, since it uses less digits than its factorization.

915921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33932 (or 33926 counting only the distinct ones).

The product of its digits is 810, while the sum is 27.

The square root of 915921 is about 957.0376168156. The cubic root of 915921 is about 97.1149309041.

It can be divided in two parts, 9159 and 21, that added together give a triangular number (9180 = T₁₃₅).

The spelling of 915921 in words is "nine hundred fifteen thousand, nine hundred twenty-one".