21506023128 has 64 divisors (see below), whose sum is σ = 56943531360. Its totient is φ = 6745112576.

The previous prime is 21506023093. The next prime is 21506023151. The reversal of 21506023128 is 82132060512.

It is a junction number, because it is equal to n+sod(n) for n = 21506023095 and 21506023104.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2587876 + ... + 2596172.

Almost surely, 2^21506023128 is an apocalyptic number.

It is an amenable number.

21506023128 is an abundant number, since it is smaller than the sum of its proper divisors (35437508232).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21506023128 is a wasteful number, since it uses less digits than its factorization.

21506023128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14676 (or 14672 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The spelling of 21506023128 in words is "twenty-one billion, five hundred six million, twenty-three thousand, one hundred twenty-eight".