21475684221 has 8 divisors (see below), whose sum is σ = 28638954240. Its totient is φ = 14314768512.

The previous prime is 21475684207. The next prime is 21475684229. The reversal of 21475684221 is 12248657412.

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

It is not a de Polignac number, because 21475684221 - 2¹⁸ = 21475422077 is a prime.

It is a super-2 number, since 2×21475684221² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21475684229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 567181 + ... + 603858.

It is an arithmetic number, because the mean of its divisors is an integer number (3579869280).

Almost surely, 2^21475684221 is an apocalyptic number.

It is an amenable number.

21475684221 is a deficient number, since it is larger than the sum of its proper divisors (7163270019).

21475684221 is a wasteful number, since it uses less digits than its factorization.

21475684221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1177155.

The product of its digits is 215040, while the sum is 42.

The spelling of 21475684221 in words is "twenty-one billion, four hundred seventy-five million, six hundred eighty-four thousand, two hundred twenty-one".