1221099811 has 2 divisors, whose sum is σ = 1221099812. Its totient is φ = 1221099810.

The previous prime is 1221099791. The next prime is 1221099823. The reversal of 1221099811 is 1189901221.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1221099811 - 2⁵ = 1221099779 is a prime.

It is not a weakly prime, because it can be changed into another prime (1221099871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610549905 + 610549906.

It is an arithmetic number, because the mean of its divisors is an integer number (610549906).

Almost surely, 2^1221099811 is an apocalyptic number.

1221099811 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221099811 is an equidigital number, since it uses as much as digits as its factorization.

1221099811 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 34.

The square root of 1221099811 is about 34944.2385952248. The cubic root of 1221099811 is about 1068.8507213489.

The spelling of 1221099811 in words is "one billion, two hundred twenty-one million, ninety-nine thousand, eight hundred eleven".