21210302191 has 4 divisors (see below), whose sum is σ = 22841863912. Its totient is φ = 19578740472.

The previous prime is 21210302189. The next prime is 21210302251. The reversal of 21210302191 is 19120301212.

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

It is a cyclic number.

It is not a de Polignac number, because 21210302191 - 2¹ = 21210302189 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 (21210302101) 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, 815780841 + ... + 815780866.

It is an arithmetic number, because the mean of its divisors is an integer number (5710465978).

Almost surely, 2^21210302191 is an apocalyptic number.

21210302191 is a deficient number, since it is larger than the sum of its proper divisors (1631561721).

21210302191 is a wasteful number, since it uses less digits than its factorization.

21210302191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631561720.

The product of its (nonzero) digits is 216, while the sum is 22.

The spelling of 21210302191 in words is "twenty-one billion, two hundred ten million, three hundred two thousand, one hundred ninety-one".