21723723212917 has 4 divisors (see below), whose sum is σ = 23698607141376. Its totient is φ = 19748839284460.

The previous prime is 21723723212887. The next prime is 21723723212921. The reversal of 21723723212917 is 71921232732712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21723723212917 - 2¹⁵ = 21723723180149 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 (21723723212977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 987441964213 + ... + 987441964234.

It is an arithmetic number, because the mean of its divisors is an integer number (5924651785344).

Almost surely, 2^{21723723212917} is an apocalyptic number.

It is an amenable number.

21723723212917 is a deficient number, since it is larger than the sum of its proper divisors (1974883928459).

21723723212917 is a wasteful number, since it uses less digits than its factorization.

21723723212917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1974883928458.

The product of its digits is 889056, while the sum is 49.

The spelling of 21723723212917 in words is "twenty-one trillion, seven hundred twenty-three billion, seven hundred twenty-three million, two hundred twelve thousand, nine hundred seventeen".