21164431215 has 16 divisors (see below), whose sum is σ = 33865802208. Its totient is φ = 11286792576.

The previous prime is 21164431147. The next prime is 21164431219. The reversal of 21164431215 is 51213446112.

It is not a de Polignac number, because 21164431215 - 2¹³ = 21164423023 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164431219) 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, 165037 + ... + 263753.

It is an arithmetic number, because the mean of its divisors is an integer number (2116612638).

Almost surely, 2^21164431215 is an apocalyptic number.

21164431215 is a deficient number, since it is larger than the sum of its proper divisors (12701370993).

21164431215 is a wasteful number, since it uses less digits than its factorization.

21164431215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113018.

The product of its digits is 5760, while the sum is 30.

Adding to 21164431215 its reverse (51213446112), we get a palindrome (72377877327).

The spelling of 21164431215 in words is "twenty-one billion, one hundred sixty-four million, four hundred thirty-one thousand, two hundred fifteen".