21718172453 has 4 divisors (see below), whose sum is σ = 21728600928. Its totient is φ = 21707743980.

The previous prime is 21718172447. The next prime is 21718172459. The reversal of 21718172453 is 35427181712.

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 an interprime number because it is at equal distance from previous prime (21718172447) and next prime (21718172459).

It is a cyclic number.

It is not a de Polignac number, because 21718172453 - 2⁶ = 21718172389 is a prime.

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 21718172453.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21718172459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5211113 + ... + 5215278.

It is an arithmetic number, because the mean of its divisors is an integer number (5432150232).

Almost surely, 2^21718172453 is an apocalyptic number.

It is an amenable number.

21718172453 is a deficient number, since it is larger than the sum of its proper divisors (10428475).

21718172453 is a wasteful number, since it uses less digits than its factorization.

21718172453 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10428474.

The product of its digits is 94080, while the sum is 41.

The spelling of 21718172453 in words is "twenty-one billion, seven hundred eighteen million, one hundred seventy-two thousand, four hundred fifty-three".