918685221 has 4 divisors (see below), whose sum is σ = 1224913632. Its totient is φ = 612456812.

The previous prime is 918685189. The next prime is 918685223. The reversal of 918685221 is 122586819.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 918685221 - 2⁵ = 918685189 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (918685223) 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, 153114201 + ... + 153114206.

It is an arithmetic number, because the mean of its divisors is an integer number (306228408).

Almost surely, 2^918685221 is an apocalyptic number.

It is an amenable number.

918685221 is a deficient number, since it is larger than the sum of its proper divisors (306228411).

918685221 is a wasteful number, since it uses less digits than its factorization.

918685221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306228410.

The product of its digits is 69120, while the sum is 42.

The square root of 918685221 is about 30309.8205372450. The cubic root of 918685221 is about 972.1252939723.

The spelling of 918685221 in words is "nine hundred eighteen million, six hundred eighty-five thousand, two hundred twenty-one".