21530217179 has 4 divisors (see below), whose sum is σ = 21531479640. Its totient is φ = 21528954720.

The previous prime is 21530217173. The next prime is 21530217221. The reversal of 21530217179 is 97171203512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21530217179 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21530217173) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 605294 + ... + 639875.

It is an arithmetic number, because the mean of its divisors is an integer number (5382869910).

Almost surely, 2^21530217179 is an apocalyptic number.

21530217179 is a deficient number, since it is larger than the sum of its proper divisors (1262461).

21530217179 is a wasteful number, since it uses less digits than its factorization.

21530217179 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1262460.

The product of its (nonzero) digits is 26460, while the sum is 38.

The spelling of 21530217179 in words is "twenty-one billion, five hundred thirty million, two hundred seventeen thousand, one hundred seventy-nine".