21530444533 has 4 divisors (see below), whose sum is σ = 23186632588. Its totient is φ = 19874256480.

The previous prime is 21530444531. The next prime is 21530444549. The reversal of 21530444533 is 33544403512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4401393649 + 17129050884 = 66343^2 + 130878^2 .

It is not a de Polignac number, because 21530444533 - 2¹ = 21530444531 is a prime.

It is a super-3 number, since 3×21530444533³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530444531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 828094008 + ... + 828094033.

It is an arithmetic number, because the mean of its divisors is an integer number (5796658147).

Almost surely, 2^21530444533 is an apocalyptic number.

It is an amenable number.

21530444533 is a deficient number, since it is larger than the sum of its proper divisors (1656188055).

21530444533 is a wasteful number, since it uses less digits than its factorization.

21530444533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1656188054.

The product of its (nonzero) digits is 86400, while the sum is 34.

The spelling of 21530444533 in words is "twenty-one billion, five hundred thirty million, four hundred forty-four thousand, five hundred thirty-three".