21155211311455 has 32 divisors (see below), whose sum is σ = 27388513152000. Its totient is φ = 15594066387072.

The previous prime is 21155211311441. The next prime is 21155211311477. The reversal of 21155211311455 is 55411311255112.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21155211311455 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 80032096 + ... + 80295994.

It is an arithmetic number, because the mean of its divisors is an integer number (855891036000).

Almost surely, 2^{21155211311455} is an apocalyptic number.

21155211311455 is a deficient number, since it is larger than the sum of its proper divisors (6233301840545).

21155211311455 is a wasteful number, since it uses less digits than its factorization.

21155211311455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266143.

The product of its digits is 30000, while the sum is 37.

Adding to 21155211311455 its reverse (55411311255112), we get a palindrome (76566522566567).

The spelling of 21155211311455 in words is "twenty-one trillion, one hundred fifty-five billion, two hundred eleven million, three hundred eleven thousand, four hundred fifty-five".