21567874849 has 2 divisors, whose sum is σ = 21567874850. Its totient is φ = 21567874848.

The previous prime is 21567874781. The next prime is 21567874903. The reversal of 21567874849 is 94847876512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11570874624 + 9997000225 = 107568^2 + 99985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21567874849 - 2¹¹ = 21567872801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21567824849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10783937424 + 10783937425.

It is an arithmetic number, because the mean of its divisors is an integer number (10783937425).

Almost surely, 2^21567874849 is an apocalyptic number.

It is an amenable number.

21567874849 is a deficient number, since it is larger than the sum of its proper divisors (1).

21567874849 is an equidigital number, since it uses as much as digits as its factorization.

21567874849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27095040, while the sum is 61.

The spelling of 21567874849 in words is "twenty-one billion, five hundred sixty-seven million, eight hundred seventy-four thousand, eight hundred forty-nine".