21455123149 has 2 divisors, whose sum is σ = 21455123150. Its totient is φ = 21455123148.

The previous prime is 21455123119. The next prime is 21455123197. The reversal of 21455123149 is 94132155412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20666075049 + 789048100 = 143757^2 + 28090^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455123149 - 2⁷ = 21455123021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21455123119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10727561574 + 10727561575.

It is an arithmetic number, because the mean of its divisors is an integer number (10727561575).

Almost surely, 2^21455123149 is an apocalyptic number.

It is an amenable number.

21455123149 is a deficient number, since it is larger than the sum of its proper divisors (1).

21455123149 is an equidigital number, since it uses as much as digits as its factorization.

21455123149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 43200, while the sum is 37.

The spelling of 21455123149 in words is "twenty-one billion, four hundred fifty-five million, one hundred twenty-three thousand, one hundred forty-nine".