918121791 has 4 divisors (see below), whose sum is σ = 1224162392. Its totient is φ = 612081192.

The previous prime is 918121783. The next prime is 918121801. The reversal of 918121791 is 197121819.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 197121819 = 3 ⋅65707273.

It is not a de Polignac number, because 918121791 - 2³ = 918121783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (918131791) 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, 153020296 + ... + 153020301.

It is an arithmetic number, because the mean of its divisors is an integer number (306040598).

Almost surely, 2^918121791 is an apocalyptic number.

918121791 is a deficient number, since it is larger than the sum of its proper divisors (306040601).

918121791 is a wasteful number, since it uses less digits than its factorization.

918121791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306040600.

The product of its digits is 9072, while the sum is 39.

The square root of 918121791 is about 30300.5245994191. The cubic root of 918121791 is about 971.9265183913.

The spelling of 918121791 in words is "nine hundred eighteen million, one hundred twenty-one thousand, seven hundred ninety-one".