21015323123 has 8 divisors (see below), whose sum is σ = 22133979648. Its totient is φ = 19913745544.

The previous prime is 21015323081. The next prime is 21015323149. The reversal of 21015323123 is 32132351012.

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 21015323123 - 2³⁴ = 3835453939 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21015323183) 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, 4267211 + ... + 4272132.

It is an arithmetic number, because the mean of its divisors is an integer number (2766747456).

Almost surely, 2^21015323123 is an apocalyptic number.

21015323123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21015323123 is a deficient number, since it is larger than the sum of its proper divisors (1118656525).

21015323123 is a wasteful number, since it uses less digits than its factorization.

21015323123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8539473.

The product of its (nonzero) digits is 1080, while the sum is 23.

Adding to 21015323123 its reverse (32132351012), we get a palindrome (53147674135).

The spelling of 21015323123 in words is "twenty-one billion, fifteen million, three hundred twenty-three thousand, one hundred twenty-three".