21878567609 has 2 divisors, whose sum is σ = 21878567610. Its totient is φ = 21878567608.

The previous prime is 21878567591. The next prime is 21878567663. The reversal of 21878567609 is 90676587812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11707240000 + 10171327609 = 108200^2 + 100853^2 .

It is a cyclic number.

It is not a de Polignac number, because 21878567609 - 2¹² = 21878563513 is a prime.

It is not a weakly prime, because it can be changed into another prime (21878567699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10939283804 + 10939283805.

It is an arithmetic number, because the mean of its divisors is an integer number (10939283805).

Almost surely, 2^21878567609 is an apocalyptic number.

It is an amenable number.

21878567609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21878567609 is an equidigital number, since it uses as much as digits as its factorization.

21878567609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10160640, while the sum is 59.

The spelling of 21878567609 in words is "twenty-one billion, eight hundred seventy-eight million, five hundred sixty-seven thousand, six hundred nine".