21161604221 has 8 divisors (see below), whose sum is σ = 21442718304. Its totient is φ = 20881113040.

The previous prime is 21161604127. The next prime is 21161604241. The reversal of 21161604221 is 12240616112.

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 21161604221 - 2³⁰ = 20087862397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161604241) 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, 87131 + ... + 223416.

It is an arithmetic number, because the mean of its divisors is an integer number (2680339788).

Almost surely, 2^21161604221 is an apocalyptic number.

It is an amenable number.

21161604221 is a deficient number, since it is larger than the sum of its proper divisors (281114083).

21161604221 is an equidigital number, since it uses as much as digits as its factorization.

21161604221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 311451.

The product of its (nonzero) digits is 1152, while the sum is 26.

The spelling of 21161604221 in words is "twenty-one billion, one hundred sixty-one million, six hundred four thousand, two hundred twenty-one".