8321720221553 has 16 divisors (see below), whose sum is σ = 8876011026240. Its totient is φ = 7774632915456.

The previous prime is 8321720221499. The next prime is 8321720221567. The reversal of 8321720221553 is 3551220271238.

It is not a de Polignac number, because 8321720221553 - 2¹⁸ = 8321719959409 is a prime.

It is a super-2 number, since 2×8321720221553² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 8321720221553.

It is not an unprimeable number, because it can be changed into a prime (8321720221753) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50547950 + ... + 50712312.

It is an arithmetic number, because the mean of its divisors is an integer number (554750689140).

Almost surely, 2^{8321720221553} is an apocalyptic number.

It is an amenable number.

8321720221553 is a deficient number, since it is larger than the sum of its proper divisors (554290804687).

8321720221553 is a wasteful number, since it uses less digits than its factorization.

8321720221553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186256.

The product of its (nonzero) digits is 201600, while the sum is 41.

The spelling of 8321720221553 in words is "eight trillion, three hundred twenty-one billion, seven hundred twenty million, two hundred twenty-one thousand, five hundred fifty-three".