21507532021173 has 8 divisors (see below), whose sum is σ = 31283682939936. Its totient is φ = 13034867891600.

The previous prime is 21507532021163. The next prime is 21507532021189. The reversal of 21507532021173 is 37112023570512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21507532021173 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507532021133) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 325871697258 + ... + 325871697323.

It is an arithmetic number, because the mean of its divisors is an integer number (3910460367492).

Almost surely, 2^{21507532021173} is an apocalyptic number.

It is an amenable number.

21507532021173 is a deficient number, since it is larger than the sum of its proper divisors (9776150918763).

21507532021173 is a wasteful number, since it uses less digits than its factorization.

21507532021173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651743394595.

The product of its (nonzero) digits is 88200, while the sum is 39.

Adding to 21507532021173 its reverse (37112023570512), we get a palindrome (58619555591685).

The spelling of 21507532021173 in words is "twenty-one trillion, five hundred seven billion, five hundred thirty-two million, twenty-one thousand, one hundred seventy-three".