20855518 has 4 divisors (see below), whose sum is σ = 31283280. Its totient is φ = 10427758.

The previous prime is 20855501. The next prime is 20855519. The reversal of 20855518 is 81555802.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81555802 = 2 ⋅40777901.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20855519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5213878 + ... + 5213881.

It is an arithmetic number, because the mean of its divisors is an integer number (7820820).

Almost surely, 2^20855518 is an apocalyptic number.

20855518 is a deficient number, since it is larger than the sum of its proper divisors (10427762).

20855518 is a wasteful number, since it uses less digits than its factorization.

20855518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10427761.

The product of its (nonzero) digits is 16000, while the sum is 34.

The square root of 20855518 is about 4566.7842077331. The cubic root of 20855518 is about 275.2582389673.

The spelling of 20855518 in words is "twenty million, eight hundred fifty-five thousand, five hundred eighteen".