21298972636549 has 2 divisors, whose sum is σ = 21298972636550. Its totient is φ = 21298972636548.

The previous prime is 21298972636537. The next prime is 21298972636573. The reversal of 21298972636549 is 94563627989212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16543986804900 + 4754985831649 = 4067430^2 + 2180593^2 .

It is a cyclic number.

It is not a de Polignac number, because 21298972636549 - 2⁷ = 21298972636421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21298978636549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10649486318274 + 10649486318275.

It is an arithmetic number, because the mean of its divisors is an integer number (10649486318275).

Almost surely, 2^{21298972636549} is an apocalyptic number.

It is an amenable number.

21298972636549 is a deficient number, since it is larger than the sum of its proper divisors (1).

21298972636549 is an equidigital number, since it uses as much as digits as its factorization.

21298972636549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 705438720, while the sum is 73.

The spelling of 21298972636549 in words is "twenty-one trillion, two hundred ninety-eight billion, nine hundred seventy-two million, six hundred thirty-six thousand, five hundred forty-nine".