21500551255111 has 2 divisors, whose sum is σ = 21500551255112. Its totient is φ = 21500551255110.

The previous prime is 21500551255037. The next prime is 21500551255187. The reversal of 21500551255111 is 11155215500512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21500551255111 - 2¹⁹ = 21500550730823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21500551258111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750275627555 + 10750275627556.

It is an arithmetic number, because the mean of its divisors is an integer number (10750275627556).

Almost surely, 2^{21500551255111} is an apocalyptic number.

21500551255111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500551255111 is an equidigital number, since it uses as much as digits as its factorization.

21500551255111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12500, while the sum is 34.

Adding to 21500551255111 its reverse (11155215500512), we get a palindrome (32655766755623).

The spelling of 21500551255111 in words is "twenty-one trillion, five hundred billion, five hundred fifty-one million, two hundred fifty-five thousand, one hundred eleven".