21516211517 has 16 divisors (see below), whose sum is σ = 23011817472. Its totient is φ = 20047084800.

The previous prime is 21516211513. The next prime is 21516211529. The reversal of 21516211517 is 71511261512.

It is a cyclic number.

It is not a de Polignac number, because 21516211517 - 2² = 21516211513 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516211513) 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, 737828 + ... + 766434.

It is an arithmetic number, because the mean of its divisors is an integer number (1438238592).

Almost surely, 2^21516211517 is an apocalyptic number.

It is an amenable number.

21516211517 is a deficient number, since it is larger than the sum of its proper divisors (1495605955).

21516211517 is a wasteful number, since it uses less digits than its factorization.

21516211517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29068.

The product of its digits is 4200, while the sum is 32.

The spelling of 21516211517 in words is "twenty-one billion, five hundred sixteen million, two hundred eleven thousand, five hundred seventeen".