21545554105249 has 2 divisors, whose sum is σ = 21545554105250. Its totient is φ = 21545554105248.

The previous prime is 21545554105123. The next prime is 21545554105331. The reversal of 21545554105249 is 94250145554512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17616219220224 + 3929334885025 = 4197168^2 + 1982255^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545554105249 - 2¹⁹ = 21545553580961 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21545554105196 and 21545554105205.

It is not a weakly prime, because it can be changed into another prime (21545554105349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772777052624 + 10772777052625.

It is an arithmetic number, because the mean of its divisors is an integer number (10772777052625).

Almost surely, 2^{21545554105249} is an apocalyptic number.

It is an amenable number.

21545554105249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545554105249 is an equidigital number, since it uses as much as digits as its factorization.

21545554105249 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7200000, while the sum is 52.

The spelling of 21545554105249 in words is "twenty-one trillion, five hundred forty-five billion, five hundred fifty-four million, one hundred five thousand, two hundred forty-nine".