21215440000 has 80 divisors (see below), whose sum is σ = 52814711070. Its totient is φ = 8486144000.

The previous prime is 21215439997. The next prime is 21215440007. The reversal of 21215440000 is 4451212.

It can be written as a sum of positive squares in 5 ways, for example, as 748131904 + 20467308096 = 27352^2 + 143064^2 .

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 21215440000.

It is not an unprimeable number, because it can be changed into a prime (21215440007) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 52597 + ... + 212596.

Almost surely, 2^21215440000 is an apocalyptic number.

21215440000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21215440000 is an abundant number, since it is smaller than the sum of its proper divisors (31599271070).

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

21215440000 is an frugal number, since it uses more digits than its factorization.

21215440000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265227 (or 265200 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

Adding to 21215440000 its reverse (4451212), we get a palindrome (21219891212).

The spelling of 21215440000 in words is "twenty-one billion, two hundred fifteen million, four hundred forty thousand".