20218540 has 24 divisors (see below), whose sum is σ = 42788592. Its totient is φ = 8024640.

The previous prime is 20218537. The next prime is 20218547. The reversal of 20218540 is 4581202.

It is not an unprimeable number, because it can be changed into a prime (20218547) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1239 + ... + 6478.

It is an arithmetic number, because the mean of its divisors is an integer number (1782858).

Almost surely, 2^20218540 is an apocalyptic number.

20218540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20218540 is an abundant number, since it is smaller than the sum of its proper divisors (22570052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20218540 is a wasteful number, since it uses less digits than its factorization.

20218540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7857 (or 7855 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 20218540 is about 4496.5030857323. The cubic root of 20218540 is about 272.4268636316.

Adding to 20218540 its reverse (4581202), we get a palindrome (24799742).

The spelling of 20218540 in words is "twenty million, two hundred eighteen thousand, five hundred forty".