915993121 has 4 divisors (see below), whose sum is σ = 916087572. Its totient is φ = 915898672.

The previous prime is 915993119. The next prime is 915993131. The reversal of 915993121 is 121399519.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 702833121 + 213160000 = 26511^2 + 14600^2 .

It is a cyclic number.

It is not a de Polignac number, because 915993121 - 2¹ = 915993119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (915993131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30766 + ... + 52711.

It is an arithmetic number, because the mean of its divisors is an integer number (229021893).

Almost surely, 2^915993121 is an apocalyptic number.

It is an amenable number.

915993121 is a deficient number, since it is larger than the sum of its proper divisors (94451).

915993121 is a wasteful number, since it uses less digits than its factorization.

915993121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94450.

The product of its digits is 21870, while the sum is 40.

The square root of 915993121 is about 30265.3782563509. The cubic root of 915993121 is about 971.1747982921.

The spelling of 915993121 in words is "nine hundred fifteen million, nine hundred ninety-three thousand, one hundred twenty-one".