20017720 has 16 divisors (see below), whose sum is σ = 45039960. Its totient is φ = 8007072.

The previous prime is 20017709. The next prime is 20017759. The reversal of 20017720 is 2771002.

It is a super-2 number, since 2×20017720² = 801418227996800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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, 250182 + ... + 250261.

Almost surely, 2^20017720 is an apocalyptic number.

20017720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20017720 is an abundant number, since it is smaller than the sum of its proper divisors (25022240).

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

20017720 is a wasteful number, since it uses less digits than its factorization.

20017720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500454 (or 500450 counting only the distinct ones).

The product of its (nonzero) digits is 196, while the sum is 19.

The square root of 20017720 is about 4474.1166725958. The cubic root of 20017720 is about 271.5219037958.

Adding to 20017720 its reverse (2771002), we get a palindrome (22788722).

The spelling of 20017720 in words is "twenty million, seventeen thousand, seven hundred twenty".