20506418 has 4 divisors (see below), whose sum is σ = 30759630. Its totient is φ = 10253208.

The previous prime is 20506417. The next prime is 20506427. The reversal of 20506418 is 81460502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81460502 = 2 ⋅40730251.

It can be written as a sum of positive squares in only one way, i.e., 11404129 + 9102289 = 3377^2 + 3017^2 .

It is not an unprimeable number, because it can be changed into a prime (20506417) 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 as a sum of consecutive naturals, namely, 5126603 + ... + 5126606.

Almost surely, 2^20506418 is an apocalyptic number.

20506418 is a deficient number, since it is larger than the sum of its proper divisors (10253212).

20506418 is a wasteful number, since it uses less digits than its factorization.

20506418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10253211.

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 20506418 is about 4528.4012631391. The cubic root of 20506418 is about 273.7137419226.

The spelling of 20506418 in words is "twenty million, five hundred six thousand, four hundred eighteen".