1221863 has 2 divisors, whose sum is σ = 1221864. Its totient is φ = 1221862.

The previous prime is 1221853. The next prime is 1221907. The reversal of 1221863 is 3681221.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1221863 - 2¹⁰ = 1220839 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610931 + 610932.

It is an arithmetic number, because the mean of its divisors is an integer number (610932).

2^1221863 is an apocalyptic number.

1221863 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221863 is an equidigital number, since it uses as much as digits as its factorization.

1221863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 23.

The square root of 1221863 is about 1105.3791204831. The cubic root of 1221863 is about 106.9073352679.

The spelling of 1221863 in words is "one million, two hundred twenty-one thousand, eight hundred sixty-three".