21556421753 has 8 divisors (see below), whose sum is σ = 22825757088. Its totient is φ = 20287232064.

The previous prime is 21556421749. The next prime is 21556421771. The reversal of 21556421753 is 35712465512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21556421753 - 2² = 21556421749 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21556421753.

It is not an unprimeable number, because it can be changed into a prime (21556421713) 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 7 ways as a sum of consecutive naturals, for example, 468350 + ... + 512312.

It is an arithmetic number, because the mean of its divisors is an integer number (2853219636).

Almost surely, 2^21556421753 is an apocalyptic number.

It is an amenable number.

21556421753 is a deficient number, since it is larger than the sum of its proper divisors (1269335335).

21556421753 is a wasteful number, since it uses less digits than its factorization.

21556421753 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72823.

The product of its digits is 252000, while the sum is 41.

The spelling of 21556421753 in words is "twenty-one billion, five hundred fifty-six million, four hundred twenty-one thousand, seven hundred fifty-three".