21517215321643 has 48 divisors (see below), whose sum is σ = 23428918204416. Its totient is φ = 19702873745280.

The previous prime is 21517215321601. The next prime is 21517215321653. The reversal of 21517215321643 is 34612351271512.

It is not a de Polignac number, because 21517215321643 - 2²⁹ = 21516678450731 is a prime.

It is a super-3 number, since 3×21517215321643³ (a number of 41 digits) contains 333 as substring.

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 21517215321643.

It is not an unprimeable number, because it can be changed into a prime (21517215321653) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5988647055 + ... + 5988650647.

It is an arithmetic number, because the mean of its divisors is an integer number (488102462592).

Almost surely, 2^{21517215321643} is an apocalyptic number.

21517215321643 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21517215321643 is a deficient number, since it is larger than the sum of its proper divisors (1911702882773).

21517215321643 is a wasteful number, since it uses less digits than its factorization.

21517215321643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4264 (or 4037 counting only the distinct ones).

The product of its digits is 302400, while the sum is 43.

The spelling of 21517215321643 in words is "twenty-one trillion, five hundred seventeen billion, two hundred fifteen million, three hundred twenty-one thousand, six hundred forty-three".