21864513215 has 16 divisors (see below), whose sum is σ = 26558733600. Its totient is φ = 17278339200.

The previous prime is 21864513163. The next prime is 21864513217. The reversal of 21864513215 is 51231546812.

It is not a de Polignac number, because 21864513215 - 2¹⁰ = 21864512191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21864513217) 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, 128165 + ... + 245265.

It is an arithmetic number, because the mean of its divisors is an integer number (1659920850).

Almost surely, 2^21864513215 is an apocalyptic number.

21864513215 is a deficient number, since it is larger than the sum of its proper divisors (4694220385).

21864513215 is a wasteful number, since it uses less digits than its factorization.

21864513215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117562.

The product of its digits is 57600, while the sum is 38.

The spelling of 21864513215 in words is "twenty-one billion, eight hundred sixty-four million, five hundred thirteen thousand, two hundred fifteen".