21212020320 has 96 divisors (see below), whose sum is σ = 68973327360. Its totient is φ = 5474065920.

The previous prime is 21212020267. The next prime is 21212020369. The reversal of 21212020320 is 2302021212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

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 21212020320.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 697890 + ... + 727649.

It is an arithmetic number, because the mean of its divisors is an integer number (718472160).

Almost surely, 2^21212020320 is an apocalyptic number.

21212020320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21212020320 is an abundant number, since it is smaller than the sum of its proper divisors (47761307040).

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

21212020320 is a wasteful number, since it uses less digits than its factorization.

21212020320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1425588 (or 1425580 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

Adding to 21212020320 its reverse (2302021212), we get a palindrome (23514041532).

The spelling of 21212020320 in words is "twenty-one billion, two hundred twelve million, twenty thousand, three hundred twenty".