21533244421 has 8 divisors (see below), whose sum is σ = 23190787424. Its totient is φ = 19875864240.

The previous prime is 21533244347. The next prime is 21533244451. The reversal of 21533244421 is 12444233512.

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

It is a cyclic number.

It is not a de Polignac number, because 21533244421 - 2¹³ = 21533236229 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533244451) 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, 507766 + ... + 548536.

It is an arithmetic number, because the mean of its divisors is an integer number (2898848428).

Almost surely, 2^21533244421 is an apocalyptic number.

It is an amenable number.

21533244421 is a deficient number, since it is larger than the sum of its proper divisors (1657543003).

21533244421 is a wasteful number, since it uses less digits than its factorization.

21533244421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81411.

The product of its digits is 23040, while the sum is 31.

Adding to 21533244421 its reverse (12444233512), we get a palindrome (33977477933).

The spelling of 21533244421 in words is "twenty-one billion, five hundred thirty-three million, two hundred forty-four thousand, four hundred twenty-one".