20618537 has 4 divisors (see below), whose sum is σ = 21007620. Its totient is φ = 20229456.

The previous prime is 20618527. The next prime is 20618539. The reversal of 20618537 is 73581602.

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 18498601 + 2119936 = 4301^2 + 1456^2 .

It is a cyclic number.

It is not a de Polignac number, because 20618537 - 2¹⁸ = 20356393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20618539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 194462 + ... + 194567.

It is an arithmetic number, because the mean of its divisors is an integer number (5251905).

Almost surely, 2^20618537 is an apocalyptic number.

It is an amenable number.

20618537 is a deficient number, since it is larger than the sum of its proper divisors (389083).

20618537 is an equidigital number, since it uses as much as digits as its factorization.

20618537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 389082.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20618537 is about 4540.7639225135. The cubic root of 20618537 is about 274.2116795343.

The spelling of 20618537 in words is "twenty million, six hundred eighteen thousand, five hundred thirty-seven".