221660513 has 2 divisors, whose sum is σ = 221660514. Its totient is φ = 221660512.

The previous prime is 221660503. The next prime is 221660539. The reversal of 221660513 is 315066122.

It is an a-pointer prime, because the next prime (221660539) can be obtained adding 221660513 to its sum of digits (26).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 197767969 + 23892544 = 14063^2 + 4888^2 .

It is a cyclic number.

It is not a de Polignac number, because 221660513 - 2⁶ = 221660449 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (221660503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110830256 + 110830257.

It is an arithmetic number, because the mean of its divisors is an integer number (110830257).

Almost surely, 2^221660513 is an apocalyptic number.

It is an amenable number.

221660513 is a deficient number, since it is larger than the sum of its proper divisors (1).

221660513 is an equidigital number, since it uses as much as digits as its factorization.

221660513 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 221660513 is about 14888.2676292442. The cubic root of 221660513 is about 605.1960869754.

The spelling of 221660513 in words is "two hundred twenty-one million, six hundred sixty thousand, five hundred thirteen".