21530155123 has 8 divisors (see below), whose sum is σ = 23190967296. Its totient is φ = 19929736200.

The previous prime is 21530155117. The next prime is 21530155181. The reversal of 21530155123 is 32155103512.

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 21530155123 - 2²⁹ = 20993284211 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21530155091 and 21530155100.

It is not an unprimeable number, because it can be changed into a prime (21530155103) 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, 15097573 + ... + 15098998.

It is an arithmetic number, because the mean of its divisors is an integer number (2898870912).

Almost surely, 2^21530155123 is an apocalyptic number.

21530155123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21530155123 is a deficient number, since it is larger than the sum of its proper divisors (1660812173).

21530155123 is a wasteful number, since it uses less digits than its factorization.

21530155123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30196625.

The product of its (nonzero) digits is 4500, while the sum is 28.

Adding to 21530155123 its reverse (32155103512), we get a palindrome (53685258635).

The spelling of 21530155123 in words is "twenty-one billion, five hundred thirty million, one hundred fifty-five thousand, one hundred twenty-three".