21505114211 has 16 divisors (see below), whose sum is σ = 25373736960. Its totient is φ = 17840826720.

The previous prime is 21505114207. The next prime is 21505114217. The reversal of 21505114211 is 11241150512.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21505114211 - 2² = 21505114207 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21505114217) 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, 167891 + ... + 266828.

It is an arithmetic number, because the mean of its divisors is an integer number (1585858560).

Almost surely, 2^21505114211 is an apocalyptic number.

21505114211 is a deficient number, since it is larger than the sum of its proper divisors (3868622749).

21505114211 is a wasteful number, since it uses less digits than its factorization.

21505114211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 434954.

The product of its (nonzero) digits is 400, while the sum is 23.

Adding to 21505114211 its reverse (11241150512), we get a palindrome (32746264723).

The spelling of 21505114211 in words is "twenty-one billion, five hundred five million, one hundred fourteen thousand, two hundred eleven".