1221811 has 2 divisors, whose sum is σ = 1221812. Its totient is φ = 1221810.

The previous prime is 1221793. The next prime is 1221821. The reversal of 1221811 is 1181221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221811 - 2⁹ = 1221299 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610905 + 610906.

It is an arithmetic number, because the mean of its divisors is an integer number (610906).

2^1221811 is an apocalyptic number.

1221811 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221811 is an equidigital number, since it uses as much as digits as its factorization.

1221811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32, while the sum is 16.

The square root of 1221811 is about 1105.3555988911. The cubic root of 1221811 is about 106.9058186603.

The spelling of 1221811 in words is "one million, two hundred twenty-one thousand, eight hundred eleven".