21221605164041 has 4 divisors (see below), whose sum is σ = 21221634321300. Its totient is φ = 21221576006784.

The previous prime is 21221605164031. The next prime is 21221605164049. The reversal of 21221605164041 is 14046150612212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10985220844816 + 10236384319225 = 3314396^2 + 3199435^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221605164041 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221605163992 and 21221605164010.

It is not an unprimeable number, because it can be changed into a prime (21221605164049) 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, 13458176 + ... + 14952113.

It is an arithmetic number, because the mean of its divisors is an integer number (5305408580325).

Almost surely, 2^{21221605164041} is an apocalyptic number.

It is an amenable number.

21221605164041 is a deficient number, since it is larger than the sum of its proper divisors (29157259).

21221605164041 is an equidigital number, since it uses as much as digits as its factorization.

21221605164041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29157258.

The product of its (nonzero) digits is 23040, while the sum is 35.

Adding to 21221605164041 its reverse (14046150612212), we get a palindrome (35267755776253).

The spelling of 21221605164041 in words is "twenty-one trillion, two hundred twenty-one billion, six hundred five million, one hundred sixty-four thousand, forty-one".