18520657 has 4 divisors (see below), whose sum is σ = 18539620. Its totient is φ = 18501696.

The previous prime is 18520613. The next prime is 18520693. The reversal of 18520657 is 75602581.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 75602581 = 37 ⋅2043313.

It can be written as a sum of positive squares in 2 ways, for example, as 14868736 + 3651921 = 3856^2 + 1911^2 .

It is a cyclic number.

It is not a de Polignac number, because 18520657 - 2¹¹ = 18518609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18524657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7932 + ... + 9997.

It is an arithmetic number, because the mean of its divisors is an integer number (4634905).

Almost surely, 2^18520657 is an apocalyptic number.

It is an amenable number.

18520657 is a deficient number, since it is larger than the sum of its proper divisors (18963).

18520657 is a wasteful number, since it uses less digits than its factorization.

18520657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18962.

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 18520657 is about 4303.5632910415. The cubic root of 18520657 is about 264.5770254860.

The spelling of 18520657 in words is "eighteen million, five hundred twenty thousand, six hundred fifty-seven".