221505556651 has 2 divisors, whose sum is σ = 221505556652. Its totient is φ = 221505556650.

The previous prime is 221505556567. The next prime is 221505556663. The reversal of 221505556651 is 156655505122.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221505556651 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 221505556598 and 221505556607.

It is not a weakly prime, because it can be changed into another prime (221505556681) 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, 110752778325 + 110752778326.

It is an arithmetic number, because the mean of its divisors is an integer number (110752778326).

Almost surely, 2^221505556651 is an apocalyptic number.

221505556651 is a deficient number, since it is larger than the sum of its proper divisors (1).

221505556651 is an equidigital number, since it uses as much as digits as its factorization.

221505556651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 450000, while the sum is 43.

The spelling of 221505556651 in words is "two hundred twenty-one billion, five hundred five million, five hundred fifty-six thousand, six hundred fifty-one".