21320220436 has 12 divisors (see below), whose sum is σ = 37470517812. Its totient is φ = 10614358208.

The previous prime is 21320220433. The next prime is 21320220437. The reversal of 21320220436 is 63402202312.

It can be written as a sum of positive squares in 2 ways, for example, as 2631690000 + 18688530436 = 51300^2 + 136706^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21320220436.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21320220433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11436955 + ... + 11438818.

It is an arithmetic number, because the mean of its divisors is an integer number (3122543151).

Almost surely, 2^21320220436 is an apocalyptic number.

It is an amenable number.

21320220436 is a deficient number, since it is larger than the sum of its proper divisors (16150297376).

21320220436 is a wasteful number, since it uses less digits than its factorization.

21320220436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22876010 (or 22876008 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 25.

Adding to 21320220436 its reverse (63402202312), we get a palindrome (84722422748).

The spelling of 21320220436 in words is "twenty-one billion, three hundred twenty million, two hundred twenty thousand, four hundred thirty-six".