20209720 has 32 divisors (see below), whose sum is σ = 46584720. Its totient is φ = 7886080.

The previous prime is 20209691. The next prime is 20209741. The reversal of 20209720 is 2790202.

It is a junction number, because it is equal to n+sod(n) for n = 20209691 and 20209700.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4522 + ... + 7801.

Almost surely, 2^20209720 is an apocalyptic number.

20209720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20209720 is an abundant number, since it is smaller than the sum of its proper divisors (26375000).

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

20209720 is a wasteful number, since it uses less digits than its factorization.

20209720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12375 (or 12371 counting only the distinct ones).

The product of its (nonzero) digits is 504, while the sum is 22.

The square root of 20209720 is about 4495.5222166062. The cubic root of 20209720 is about 272.3872439820.

Adding to 20209720 its reverse (2790202), we get a palindrome (22999922).

The spelling of 20209720 in words is "twenty million, two hundred nine thousand, seven hundred twenty".