21516784727 has 2 divisors, whose sum is σ = 21516784728. Its totient is φ = 21516784726.

The previous prime is 21516784721. The next prime is 21516784741. The reversal of 21516784727 is 72748761512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21516784727 - 2⁴ = 21516784711 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21516784721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758392363 + 10758392364.

It is an arithmetic number, because the mean of its divisors is an integer number (10758392364).

Almost surely, 2^21516784727 is an apocalyptic number.

21516784727 is a deficient number, since it is larger than the sum of its proper divisors (1).

21516784727 is an equidigital number, since it uses as much as digits as its factorization.

21516784727 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1317120, while the sum is 50.

The spelling of 21516784727 in words is "twenty-one billion, five hundred sixteen million, seven hundred eighty-four thousand, seven hundred twenty-seven".