21724376181 has 4 divisors (see below), whose sum is σ = 28965834912. Its totient is φ = 14482917452.

The previous prime is 21724376147. The next prime is 21724376189. The reversal of 21724376181 is 18167342712.

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 a cyclic number.

It is not a de Polignac number, because 21724376181 - 2⁹ = 21724375669 is a prime.

It is a super-2 number, since 2×21724376181² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21724376189) 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, 3620729361 + ... + 3620729366.

It is an arithmetic number, because the mean of its divisors is an integer number (7241458728).

Almost surely, 2^21724376181 is an apocalyptic number.

It is an amenable number.

21724376181 is a deficient number, since it is larger than the sum of its proper divisors (7241458731).

21724376181 is an equidigital number, since it uses as much as digits as its factorization.

21724376181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7241458730.

The product of its digits is 112896, while the sum is 42.

The spelling of 21724376181 in words is "twenty-one billion, seven hundred twenty-four million, three hundred seventy-six thousand, one hundred eighty-one".