11356721221 has 2 divisors, whose sum is σ = 11356721222. Its totient is φ = 11356721220.

The previous prime is 11356721219. The next prime is 11356721251. The reversal of 11356721221 is 12212765311.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8558840196 + 2797881025 = 92514^2 + 52895^2 .

It is a cyclic number.

It is not a de Polignac number, because 11356721221 - 2¹ = 11356721219 is a prime.

Together with 11356721219, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11356721251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5678360610 + 5678360611.

It is an arithmetic number, because the mean of its divisors is an integer number (5678360611).

Almost surely, 2^11356721221 is an apocalyptic number.

It is an amenable number.

11356721221 is a deficient number, since it is larger than the sum of its proper divisors (1).

11356721221 is an equidigital number, since it uses as much as digits as its factorization.

11356721221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 31.

The spelling of 11356721221 in words is "eleven billion, three hundred fifty-six million, seven hundred twenty-one thousand, two hundred twenty-one".