221505566651 has 2 divisors, whose sum is σ = 221505566652. Its totient is φ = 221505566650.

The previous prime is 221505566603. The next prime is 221505566717. The reversal of 221505566651 is 156665505122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221505566651 - 2¹⁰ = 221505565627 is a prime.

It is not a weakly prime, because it can be changed into another prime (221505556651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110752783325 + 110752783326.

It is an arithmetic number, because the mean of its divisors is an integer number (110752783326).

Almost surely, 2^221505566651 is an apocalyptic number.

221505566651 is a deficient number, since it is larger than the sum of its proper divisors (1).

221505566651 is an equidigital number, since it uses as much as digits as its factorization.

221505566651 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 540000, while the sum is 44.

The spelling of 221505566651 in words is "two hundred twenty-one billion, five hundred five million, five hundred sixty-six thousand, six hundred fifty-one".