21006525123 has 12 divisors (see below), whose sum is σ = 31121893720. Its totient is φ = 14003848008.

The previous prime is 21006525109. The next prime is 21006525139. The reversal of 21006525123 is 32152560012.

It is a happy number.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

21006525123 is a `hidden beast` number, since 2 + 1 + 0 + 0 + 652 + 5 + 1 + 2 + 3 = 666.

It is not a de Polignac number, because 21006525123 - 2⁵ = 21006525091 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21006525923) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 739165 + ... + 767057.

Almost surely, 2^21006525123 is an apocalyptic number.

21006525123 is a deficient number, since it is larger than the sum of its proper divisors (10115368597).

21006525123 is an frugal number, since it uses more digits than its factorization.

21006525123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55795 (or 27896 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Multiplying 21006525123 by its sum of digits (27), we get a square (567176178321 = 753111²).

21006525123 divided by its sum of digits (27) gives a square (778019449 = 27893²).

The spelling of 21006525123 in words is "twenty-one billion, six million, five hundred twenty-five thousand, one hundred twenty-three".