21540024691 has 2 divisors, whose sum is σ = 21540024692. Its totient is φ = 21540024690.

The previous prime is 21540024523. The next prime is 21540024707. The reversal of 21540024691 is 19642004512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21540024691 - 2¹¹ = 21540022643 is a prime.

It is not a weakly prime, because it can be changed into another prime (21540024391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770012345 + 10770012346.

It is an arithmetic number, because the mean of its divisors is an integer number (10770012346).

Almost surely, 2^21540024691 is an apocalyptic number.

21540024691 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540024691 is an equidigital number, since it uses as much as digits as its factorization.

21540024691 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 34.

The spelling of 21540024691 in words is "twenty-one billion, five hundred forty million, twenty-four thousand, six hundred ninety-one".