18121597 has 4 divisors (see below), whose sum is σ = 19515580. Its totient is φ = 16727616.

The previous prime is 18121589. The next prime is 18121603. The reversal of 18121597 is 79512181.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8173881 + 9947716 = 2859^2 + 3154^2 .

It is a cyclic number.

It is not a de Polignac number, because 18121597 - 2³ = 18121589 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 (18121517) 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, 696972 + ... + 696997.

It is an arithmetic number, because the mean of its divisors is an integer number (4878895).

Almost surely, 2^18121597 is an apocalyptic number.

It is an amenable number.

18121597 is a deficient number, since it is larger than the sum of its proper divisors (1393983).

18121597 is a wasteful number, since it uses less digits than its factorization.

18121597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1393982.

The product of its digits is 5040, while the sum is 34.

The square root of 18121597 is about 4256.9469106391. The cubic root of 18121597 is about 262.6629530927.

The spelling of 18121597 in words is "eighteen million, one hundred twenty-one thousand, five hundred ninety-seven".