21100122222521 has 2 divisors, whose sum is σ = 21100122222522. Its totient is φ = 21100122222520.

The previous prime is 21100122222493. The next prime is 21100122222523. The reversal of 21100122222521 is 12522222100112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19712143706896 + 1387978515625 = 4439836^2 + 1178125^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21100122222521 is a prime.

Together with 21100122222523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21100122222523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550061111260 + 10550061111261.

It is an arithmetic number, because the mean of its divisors is an integer number (10550061111261).

Almost surely, 2^{21100122222521} is an apocalyptic number.

It is an amenable number.

21100122222521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100122222521 is an equidigital number, since it uses as much as digits as its factorization.

21100122222521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 640, while the sum is 23.

Adding to 21100122222521 its reverse (12522222100112), we get a palindrome (33622344322633).

The spelling of 21100122222521 in words is "twenty-one trillion, one hundred billion, one hundred twenty-two million, two hundred twenty-two thousand, five hundred twenty-one".