21507387173 has 8 divisors (see below), whose sum is σ = 22298983680. Its totient is φ = 20721903840.

The previous prime is 21507387163. The next prime is 21507387197. The reversal of 21507387173 is 37178370512.

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

It is not a de Polignac number, because 21507387173 - 2¹⁰ = 21507386149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507387113) 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, 1521128 + ... + 1535201.

It is an arithmetic number, because the mean of its divisors is an integer number (2787372960).

Almost surely, 2^21507387173 is an apocalyptic number.

It is an amenable number.

21507387173 is a deficient number, since it is larger than the sum of its proper divisors (791596507).

21507387173 is a wasteful number, since it uses less digits than its factorization.

21507387173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3056587.

The product of its (nonzero) digits is 246960, while the sum is 44.

The spelling of 21507387173 in words is "twenty-one billion, five hundred seven million, three hundred eighty-seven thousand, one hundred seventy-three".