21545554105123 has 2 divisors, whose sum is σ = 21545554105124. Its totient is φ = 21545554105122.

The previous prime is 21545554104973. The next prime is 21545554105249. The reversal of 21545554105123 is 32150145554512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21545554105123 - 2¹³ = 21545554096931 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21545554105123.

It is not a weakly prime, because it can be changed into another prime (21545554105423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772777052561 + 10772777052562.

It is an arithmetic number, because the mean of its divisors is an integer number (10772777052562).

Almost surely, 2^{21545554105123} is an apocalyptic number.

21545554105123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545554105123 is an equidigital number, since it uses as much as digits as its factorization.

21545554105123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 600000, while the sum is 43.

Adding to 21545554105123 its reverse (32150145554512), we get a palindrome (53695699659635).

The spelling of 21545554105123 in words is "twenty-one trillion, five hundred forty-five billion, five hundred fifty-four million, one hundred five thousand, one hundred twenty-three".