21504660869 has 2 divisors, whose sum is σ = 21504660870. Its totient is φ = 21504660868.

The previous prime is 21504660851. The next prime is 21504660889. The reversal of 21504660869 is 96806640512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15379720225 + 6124940644 = 124015^2 + 78262^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21504660869 is a prime.

It is a super-2 number, since 2×21504660869² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21504660889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752330434 + 10752330435.

It is an arithmetic number, because the mean of its divisors is an integer number (10752330435).

Almost surely, 2^21504660869 is an apocalyptic number.

It is an amenable number.

21504660869 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504660869 is an equidigital number, since it uses as much as digits as its factorization.

21504660869 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 622080, while the sum is 47.

The spelling of 21504660869 in words is "twenty-one billion, five hundred four million, six hundred sixty thousand, eight hundred sixty-nine".