21260072221 has 4 divisors (see below), whose sum is σ = 21338522944. Its totient is φ = 21181621500.

The previous prime is 21260072219. The next prime is 21260072257. The reversal of 21260072221 is 12227006212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21260072221 - 2¹ = 21260072219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21260072321) 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, 39224955 + ... + 39225496.

It is an arithmetic number, because the mean of its divisors is an integer number (5334630736).

Almost surely, 2^21260072221 is an apocalyptic number.

It is an amenable number.

21260072221 is a deficient number, since it is larger than the sum of its proper divisors (78450723).

21260072221 is an equidigital number, since it uses as much as digits as its factorization.

21260072221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78450722.

The product of its (nonzero) digits is 1344, while the sum is 25.

Adding to 21260072221 its reverse (12227006212), we get a palindrome (33487078433).

The spelling of 21260072221 in words is "twenty-one billion, two hundred sixty million, seventy-two thousand, two hundred twenty-one".