21530206431 has 16 divisors (see below), whose sum is σ = 31927521120. Its totient is φ = 14339557440.

The previous prime is 21530206387. The next prime is 21530206433. The reversal of 21530206431 is 13460203512.

21530206431 is a `hidden beast` number, since 2 + 15 + 3 + 0 + 2 + 0 + 643 + 1 = 666.

It is not a de Polignac number, because 21530206431 - 2¹⁹ = 21529682143 is a prime.

It is a super-2 number, since 2×21530206431² (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 junction number, because it is equal to n+sod(n) for n = 21530206395 and 21530206404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530206433) 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 15 ways as a sum of consecutive naturals, for example, 358080 + ... + 413861.

It is an arithmetic number, because the mean of its divisors is an integer number (1995470070).

Almost surely, 2^21530206431 is an apocalyptic number.

21530206431 is a deficient number, since it is larger than the sum of its proper divisors (10397314689).

21530206431 is a wasteful number, since it uses less digits than its factorization.

21530206431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 772983 (or 772977 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

Adding to 21530206431 its reverse (13460203512), we get a palindrome (34990409943).

The spelling of 21530206431 in words is "twenty-one billion, five hundred thirty million, two hundred six thousand, four hundred thirty-one".