21215201215 has 12 divisors (see below), whose sum is σ = 27567209304. Its totient is φ = 15666609504.

The previous prime is 21215201209. The next prime is 21215201237. The reversal of 21215201215 is 51210251212.

It is a happy number.

It is not a de Polignac number, because 21215201215 - 2³ = 21215201207 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 12552529 + ... + 12554218.

It is an arithmetic number, because the mean of its divisors is an integer number (2297267442).

Almost surely, 2^21215201215 is an apocalyptic number.

21215201215 is a deficient number, since it is larger than the sum of its proper divisors (6352008089).

21215201215 is a wasteful number, since it uses less digits than its factorization.

21215201215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25106778 (or 25106765 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 22.

Adding to 21215201215 its reverse (51210251212), we get a palindrome (72425452427).

The spelling of 21215201215 in words is "twenty-one billion, two hundred fifteen million, two hundred one thousand, two hundred fifteen".