221621839 has 2 divisors, whose sum is σ = 221621840. Its totient is φ = 221621838.

The previous prime is 221621831. The next prime is 221621861. The reversal of 221621839 is 938126122.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 221621839 - 2³ = 221621831 is a prime.

It is equal to p_12206896 and since 221621839 and 12206896 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221621831) 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, 110810919 + 110810920.

It is an arithmetic number, because the mean of its divisors is an integer number (110810920).

Almost surely, 2^221621839 is an apocalyptic number.

221621839 is a deficient number, since it is larger than the sum of its proper divisors (1).

221621839 is an equidigital number, since it uses as much as digits as its factorization.

221621839 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 34.

The square root of 221621839 is about 14886.9687646613. The cubic root of 221621839 is about 605.1608879309.

The spelling of 221621839 in words is "two hundred twenty-one million, six hundred twenty-one thousand, eight hundred thirty-nine".