21573858091 has 2 divisors, whose sum is σ = 21573858092. Its totient is φ = 21573858090.

The previous prime is 21573858077. The next prime is 21573858157. The reversal of 21573858091 is 19085837512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21573858091 is a prime.

It is not a weakly prime, because it can be changed into another prime (21573858491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786929045 + 10786929046.

It is an arithmetic number, because the mean of its divisors is an integer number (10786929046).

Almost surely, 2^21573858091 is an apocalyptic number.

21573858091 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573858091 is an equidigital number, since it uses as much as digits as its factorization.

21573858091 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 604800, while the sum is 49.

The spelling of 21573858091 in words is "twenty-one billion, five hundred seventy-three million, eight hundred fifty-eight thousand, ninety-one".