21845978249 has 2 divisors, whose sum is σ = 21845978250. Its totient is φ = 21845978248.

The previous prime is 21845978239. The next prime is 21845978261. The reversal of 21845978249 is 94287954812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19924734025 + 1921244224 = 141155^2 + 43832^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21845978249 is a prime.

It is a super-2 number, since 2×21845978249² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21845978239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10922989124 + 10922989125.

It is an arithmetic number, because the mean of its divisors is an integer number (10922989125).

Almost surely, 2^21845978249 is an apocalyptic number.

It is an amenable number.

21845978249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21845978249 is an equidigital number, since it uses as much as digits as its factorization.

21845978249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11612160, while the sum is 59.

The spelling of 21845978249 in words is "twenty-one billion, eight hundred forty-five million, nine hundred seventy-eight thousand, two hundred forty-nine".