21086523021 has 4 divisors (see below), whose sum is σ = 28115364032. Its totient is φ = 14057682012.

The previous prime is 21086522993. The next prime is 21086523041. The reversal of 21086523021 is 12032568012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21086523021 - 2⁶ = 21086522957 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21086523021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21086523041) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3514420501 + ... + 3514420506.

It is an arithmetic number, because the mean of its divisors is an integer number (7028841008).

Almost surely, 2^21086523021 is an apocalyptic number.

It is an amenable number.

21086523021 is a deficient number, since it is larger than the sum of its proper divisors (7028841011).

21086523021 is an equidigital number, since it uses as much as digits as its factorization.

21086523021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7028841010.

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

The spelling of 21086523021 in words is "twenty-one billion, eighty-six million, five hundred twenty-three thousand, twenty-one".