21443433021 has 20 divisors (see below), whose sum is σ = 33917066172. Its totient is φ = 13454702208.

The previous prime is 21443433007. The next prime is 21443433023. The reversal of 21443433021 is 12033434412.

21443433021 is a `hidden beast` number, since 2 + 14 + 4 + 343 + 302 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 15236199225 + 6207233796 = 123435^2 + 78786^2 .

It is not a de Polignac number, because 21443433021 - 2¹⁹ = 21442908733 is a prime.

It is a super-2 number, since 2×21443433021² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443433023) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 7784910 + ... + 7787663.

Almost surely, 2^21443433021 is an apocalyptic number.

It is an amenable number.

21443433021 is a deficient number, since it is larger than the sum of its proper divisors (12473633151).

21443433021 is a wasteful number, since it uses less digits than its factorization.

21443433021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15572602 (or 15572593 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 27.

Adding to 21443433021 its reverse (12033434412), we get a palindrome (33476867433).

The spelling of 21443433021 in words is "twenty-one billion, four hundred forty-three million, four hundred thirty-three thousand, twenty-one".