21205128183 has 8 divisors (see below), whose sum is σ = 29185552896. Its totient is φ = 13680727800.

The previous prime is 21205128169. The next prime is 21205128223. The reversal of 21205128183 is 38182150212.

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

It is not a de Polignac number, because 21205128183 - 2²⁹ = 20668257271 is a prime.

It is a super-2 number, since 2×21205128183² (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 (21205128883) 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, 114005973 + ... + 114006158.

It is an arithmetic number, because the mean of its divisors is an integer number (3648194112).

Almost surely, 2^21205128183 is an apocalyptic number.

21205128183 is a deficient number, since it is larger than the sum of its proper divisors (7980424713).

21205128183 is a wasteful number, since it uses less digits than its factorization.

21205128183 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228012165.

The product of its (nonzero) digits is 7680, while the sum is 33.

Adding to 21205128183 its reverse (38182150212), we get a palindrome (59387278395).

The spelling of 21205128183 in words is "twenty-one billion, two hundred five million, one hundred twenty-eight thousand, one hundred eighty-three".