221256613 has 2 divisors, whose sum is σ = 221256614. Its totient is φ = 221256612.

The previous prime is 221256611. The next prime is 221256617. The reversal of 221256613 is 316652122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 203262049 + 17994564 = 14257^2 + 4242^2 .

It is a cyclic number.

It is not a de Polignac number, because 221256613 - 2¹ = 221256611 is a prime.

Together with 221256611, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221256611) 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, 110628306 + 110628307.

It is an arithmetic number, because the mean of its divisors is an integer number (110628307).

Almost surely, 2^221256613 is an apocalyptic number.

It is an amenable number.

221256613 is a deficient number, since it is larger than the sum of its proper divisors (1).

221256613 is an equidigital number, since it uses as much as digits as its factorization.

221256613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4320, while the sum is 28.

The square root of 221256613 is about 14874.6970725457. The cubic root of 221256613 is about 604.8282762857.

The spelling of 221256613 in words is "two hundred twenty-one million, two hundred fifty-six thousand, six hundred thirteen".