21424800657561 has 16 divisors (see below), whose sum is σ = 32652868684800. Its totient is φ = 12240660709008.

The previous prime is 21424800657529. The next prime is 21424800657599. The reversal of 21424800657561 is 16575600842412.

It is not a de Polignac number, because 21424800657561 - 2⁵ = 21424800657529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21424800657061) 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 15 ways as a sum of consecutive naturals, for example, 86645431 + ... + 86892348.

It is an arithmetic number, because the mean of its divisors is an integer number (2040804292800).

Almost surely, 2^{21424800657561} is an apocalyptic number.

21424800657561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21424800657561 is a deficient number, since it is larger than the sum of its proper divisors (11228068027239).

21424800657561 is a wasteful number, since it uses less digits than its factorization.

21424800657561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173543668.

The product of its (nonzero) digits is 3225600, while the sum is 51.

The spelling of 21424800657561 in words is "twenty-one trillion, four hundred twenty-four billion, eight hundred million, six hundred fifty-seven thousand, five hundred sixty-one".