21566610587 has 2 divisors, whose sum is σ = 21566610588. Its totient is φ = 21566610586.

The previous prime is 21566610577. The next prime is 21566610643. The reversal of 21566610587 is 78501666512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21566610587 is a prime.

It is a super-2 number, since 2×21566610587² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21566610547) 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, 10783305293 + 10783305294.

It is an arithmetic number, because the mean of its divisors is an integer number (10783305294).

Almost surely, 2^21566610587 is an apocalyptic number.

21566610587 is a deficient number, since it is larger than the sum of its proper divisors (1).

21566610587 is an equidigital number, since it uses as much as digits as its factorization.

21566610587 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 47.

The spelling of 21566610587 in words is "twenty-one billion, five hundred sixty-six million, six hundred ten thousand, five hundred eighty-seven".