20501221220 has 48 divisors (see below), whose sum is σ = 44240717808. Its totient is φ = 7974420480.

The previous prime is 20501221219. The next prime is 20501221229. The reversal of 20501221220 is 2212210502.

It can be written as a sum of positive squares in 8 ways, for example, as 8726116 + 20492495104 = 2954^2 + 143152^2 .

It is a super-2 number, since 2×20501221220² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20501221229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1533284 + ... + 1546596.

It is an arithmetic number, because the mean of its divisors is an integer number (921681621).

Almost surely, 2^20501221220 is an apocalyptic number.

20501221220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20501221220 is an abundant number, since it is smaller than the sum of its proper divisors (23739496588).

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

20501221220 is a wasteful number, since it uses less digits than its factorization.

20501221220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15440 (or 15438 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

Adding to 20501221220 its reverse (2212210502), we get a palindrome (22713431722).

The spelling of 20501221220 in words is "twenty billion, five hundred one million, two hundred twenty-one thousand, two hundred twenty".