20311620 has 96 divisors (see below), whose sum is σ = 65657088. Its totient is φ = 4595712.

The previous prime is 20311619. The next prime is 20311657. The reversal of 20311620 is 2611302.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 20311620.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 57364 + ... + 57716.

It is an arithmetic number, because the mean of its divisors is an integer number (683928).

Almost surely, 2^20311620 is an apocalyptic number.

20311620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20311620, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32828544).

20311620 is an abundant number, since it is smaller than the sum of its proper divisors (45345468).

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

20311620 is a wasteful number, since it uses less digits than its factorization.

20311620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509 (or 507 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 15.

The square root of 20311620 is about 4506.8414660381. The cubic root of 20311620 is about 272.8442805002.

Adding to 20311620 its reverse (2611302), we get a palindrome (22922922).

The spelling of 20311620 in words is "twenty million, three hundred eleven thousand, six hundred twenty".