21242443621 has 32 divisors (see below), whose sum is σ = 25122924288. Its totient is φ = 17583298560.

The previous prime is 21242443583. The next prime is 21242443657. The reversal of 21242443621 is 12634424212.

It is a cyclic number.

It is not a de Polignac number, because 21242443621 - 2⁷ = 21242443493 is a prime.

It is a super-3 number, since 3×21242443621³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242443681) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 20563321 + ... + 20564353.

It is an arithmetic number, because the mean of its divisors is an integer number (785091384).

Almost surely, 2^21242443621 is an apocalyptic number.

It is an amenable number.

21242443621 is a deficient number, since it is larger than the sum of its proper divisors (3880480667).

21242443621 is a wasteful number, since it uses less digits than its factorization.

21242443621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1741.

The product of its digits is 18432, while the sum is 31.

Adding to 21242443621 its reverse (12634424212), we get a palindrome (33876867833).

The spelling of 21242443621 in words is "twenty-one billion, two hundred forty-two million, four hundred forty-three thousand, six hundred twenty-one".