21155513215 has 16 divisors (see below), whose sum is σ = 25487370720. Its totient is φ = 16857371520.

The previous prime is 21155513213. The next prime is 21155513219. The reversal of 21155513215 is 51231555112.

It is not a de Polignac number, because 21155513215 - 2¹ = 21155513213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155513213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1377157 + ... + 1392433.

It is an arithmetic number, because the mean of its divisors is an integer number (1592960670).

Almost surely, 2^21155513215 is an apocalyptic number.

21155513215 is a deficient number, since it is larger than the sum of its proper divisors (4331857505).

21155513215 is a wasteful number, since it uses less digits than its factorization.

21155513215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16362.

The product of its digits is 7500, while the sum is 31.

The spelling of 21155513215 in words is "twenty-one billion, one hundred fifty-five million, five hundred thirteen thousand, two hundred fifteen".