21428753617 has 4 divisors (see below), whose sum is σ = 21433268736. Its totient is φ = 21424238500.

The previous prime is 21428753543. The next prime is 21428753629. The reversal of 21428753617 is 71635782412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21428753617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21428753677) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2250433 + ... + 2259934.

It is an arithmetic number, because the mean of its divisors is an integer number (5358317184).

Almost surely, 2^21428753617 is an apocalyptic number.

It is an amenable number.

21428753617 is a deficient number, since it is larger than the sum of its proper divisors (4515119).

21428753617 is an equidigital number, since it uses as much as digits as its factorization.

21428753617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4515118.

The product of its digits is 564480, while the sum is 46.

The spelling of 21428753617 in words is "twenty-one billion, four hundred twenty-eight million, seven hundred fifty-three thousand, six hundred seventeen".