21242115555 has 16 divisors (see below), whose sum is σ = 34006072320. Its totient is φ = 11322899168.

The previous prime is 21242115529. The next prime is 21242115569. The reversal of 21242115555 is 55551124212.

It is a cyclic number.

It is not a de Polignac number, because 21242115555 - 2¹¹ = 21242113507 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 361065 + ... + 415754.

It is an arithmetic number, because the mean of its divisors is an integer number (2125379520).

Almost surely, 2^21242115555 is an apocalyptic number.

21242115555 is a deficient number, since it is larger than the sum of its proper divisors (12763956765).

21242115555 is a wasteful number, since it uses less digits than its factorization.

21242115555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 778650.

The product of its digits is 20000, while the sum is 33.

Adding to 21242115555 its reverse (55551124212), we get a palindrome (76793239767).

The spelling of 21242115555 in words is "twenty-one billion, two hundred forty-two million, one hundred fifteen thousand, five hundred fifty-five".