20731216 has 40 divisors (see below), whose sum is σ = 44559648. Its totient is φ = 9264000.

The previous prime is 20731189. The next prime is 20731231. The reversal of 20731216 is 61213702.

It is a Harshad number since it is a multiple of its sum of digits (22).

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 7 ways as a sum of consecutive naturals, for example, 9771 + ... + 11701.

Almost surely, 2^20731216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20731216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22279824).

20731216 is an abundant number, since it is smaller than the sum of its proper divisors (23828432).

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

20731216 is a wasteful number, since it uses less digits than its factorization.

20731216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2011 (or 2005 counting only the distinct ones).

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

The square root of 20731216 is about 4553.1545108858. The cubic root of 20731216 is about 274.7102888373.

Adding to 20731216 its reverse (61213702), we get a palindrome (81944918).

The spelling of 20731216 in words is "twenty million, seven hundred thirty-one thousand, two hundred sixteen".