21506898136867 has 32 divisors (see below), whose sum is σ = 25493527019520. Its totient is φ = 17886140737920.

The previous prime is 21506898136849. The next prime is 21506898136877. The reversal of 21506898136867 is 76863189860512.

It is not a de Polignac number, because 21506898136867 - 2¹⁹ = 21506897612579 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21506898136796 and 21506898136805.

It is not an unprimeable number, because it can be changed into a prime (21506898136877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16045653 + ... + 17334265.

It is an arithmetic number, because the mean of its divisors is an integer number (796672719360).

Almost surely, 2^{21506898136867} is an apocalyptic number.

21506898136867 is a deficient number, since it is larger than the sum of its proper divisors (3986628882653).

21506898136867 is a wasteful number, since it uses less digits than its factorization.

21506898136867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1289683.

The product of its (nonzero) digits is 209018880, while the sum is 70.

The spelling of 21506898136867 in words is "twenty-one trillion, five hundred six billion, eight hundred ninety-eight million, one hundred thirty-six thousand, eight hundred sixty-seven".