21020302254221 has 4 divisors (see below), whose sum is σ = 21021185001852. Its totient is φ = 21019419506592.

The previous prime is 21020302254209. The next prime is 21020302254257. The reversal of 21020302254221 is 12245220302012.

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 5004218214121 + 16016084040100 = 2237011^2 + 4002010^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020302254221 is a prime.

It is a super-2 number, since 2×21020302254221² (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 (21020302254821) 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, 441338096 + ... + 441385721.

It is an arithmetic number, because the mean of its divisors is an integer number (5255296250463).

Almost surely, 2^{21020302254221} is an apocalyptic number.

It is an amenable number.

21020302254221 is a deficient number, since it is larger than the sum of its proper divisors (882747631).

21020302254221 is an equidigital number, since it uses as much as digits as its factorization.

21020302254221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 882747630.

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21020302254221 its reverse (12245220302012), we get a palindrome (33265522556233).

The spelling of 21020302254221 in words is "twenty-one trillion, twenty billion, three hundred two million, two hundred fifty-four thousand, two hundred twenty-one".