21533430125 has 16 divisors (see below), whose sum is σ = 27150784752. Its totient is φ = 17049139200.

The previous prime is 21533430091. The next prime is 21533430131. The reversal of 21533430125 is 52103433512.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 3426229156 + 18107200969 = 58534^2 + 134563^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21533430125 is a prime.

It is a super-2 number, since 2×21533430125² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 875852 + ... + 900101.

It is an arithmetic number, because the mean of its divisors is an integer number (1696924047).

Almost surely, 2^21533430125 is an apocalyptic number.

21533430125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21533430125 is a deficient number, since it is larger than the sum of its proper divisors (5617354627).

21533430125 is an equidigital number, since it uses as much as digits as its factorization.

21533430125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1776065 (or 1776055 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 29.

Adding to 21533430125 its reverse (52103433512), we get a palindrome (73636863637).

The spelling of 21533430125 in words is "twenty-one billion, five hundred thirty-three million, four hundred thirty thousand, one hundred twenty-five".