21673543091 has 2 divisors, whose sum is σ = 21673543092. Its totient is φ = 21673543090.

The previous prime is 21673543079. The next prime is 21673543093. The reversal of 21673543091 is 19034537612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21673543091 - 2³⁰ = 20599801267 is a prime.

Together with 21673543093, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21673543093) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836771545 + 10836771546.

It is an arithmetic number, because the mean of its divisors is an integer number (10836771546).

Almost surely, 2^21673543091 is an apocalyptic number.

21673543091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21673543091 is an equidigital number, since it uses as much as digits as its factorization.

21673543091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 41.

The spelling of 21673543091 in words is "twenty-one billion, six hundred seventy-three million, five hundred forty-three thousand, ninety-one".