21040041221 has 2 divisors, whose sum is σ = 21040041222. Its totient is φ = 21040041220.

The previous prime is 21040041181. The next prime is 21040041233. The reversal of 21040041221 is 12214004012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19979822500 + 1060218721 = 141350^2 + 32561^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21040041221 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21040041221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21040041241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520020610 + 10520020611.

It is an arithmetic number, because the mean of its divisors is an integer number (10520020611).

Almost surely, 2^21040041221 is an apocalyptic number.

It is an amenable number.

21040041221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040041221 is an equidigital number, since it uses as much as digits as its factorization.

21040041221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21040041221 its reverse (12214004012), we get a palindrome (33254045233).

The spelling of 21040041221 in words is "twenty-one billion, forty million, forty-one thousand, two hundred twenty-one".