21511211017 has 16 divisors (see below), whose sum is σ = 21965468800. Its totient is φ = 21061244160.

The previous prime is 21511210999. The next prime is 21511211021. The reversal of 21511211017 is 71011211512.

It is a cyclic number.

It is not a de Polignac number, because 21511211017 - 2²³ = 21502822409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21511211087) 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, 11447284 + ... + 11449162.

It is an arithmetic number, because the mean of its divisors is an integer number (1372841800).

Almost surely, 2^21511211017 is an apocalyptic number.

It is an amenable number.

21511211017 is a deficient number, since it is larger than the sum of its proper divisors (454257783).

21511211017 is a wasteful number, since it uses less digits than its factorization.

21511211017 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2896.

The product of its (nonzero) digits is 140, while the sum is 22.

Multiplying 21511211017 by its sum of digits (22), we get a palindrome (473246642374).

Adding to 21511211017 its reverse (71011211512), we get a palindrome (92522422529).

The spelling of 21511211017 in words is "twenty-one billion, five hundred eleven million, two hundred eleven thousand, seventeen".