21605357233021 has 8 divisors (see below), whose sum is σ = 21615500547704. Its totient is φ = 21595214511360.

The previous prime is 21605357233003. The next prime is 21605357233037. The reversal of 21605357233021 is 12033275350612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 924818805625 + 20680538427396 = 961675^2 + 4547586^2 .

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 21605357233021 - 2⁵ = 21605357232989 is a prime.

It is a super-2 number, since 2×21605357233021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21605357233091) 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, 83796115 + ... + 84053551.

It is an arithmetic number, because the mean of its divisors is an integer number (2701937568463).

Almost surely, 2^{21605357233021} is an apocalyptic number.

It is an amenable number.

21605357233021 is a deficient number, since it is larger than the sum of its proper divisors (10143314683).

21605357233021 is a wasteful number, since it uses less digits than its factorization.

21605357233021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296511.

The product of its (nonzero) digits is 226800, while the sum is 40.

The spelling of 21605357233021 in words is "twenty-one trillion, six hundred five billion, three hundred fifty-seven million, two hundred thirty-three thousand, twenty-one".