1211111009 has 4 divisors (see below), whose sum is σ = 1215056304. Its totient is φ = 1207165716.

The previous prime is 1211110987. The next prime is 1211111029. The reversal of 1211111009 is 9001111121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1211111009 is a prime.

It is a super-2 number, since 2×1211111009² = 2933579752241996162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1211111029) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1972187 + ... + 1972800.

It is an arithmetic number, because the mean of its divisors is an integer number (303764076).

Almost surely, 2^1211111009 is an apocalyptic number.

It is an amenable number.

1211111009 is a deficient number, since it is larger than the sum of its proper divisors (3945295).

1211111009 is an equidigital number, since it uses as much as digits as its factorization.

1211111009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3945294.

The product of its (nonzero) digits is 18, while the sum is 17.

The square root of 1211111009 is about 34801.0202292979. The cubic root of 1211111009 is about 1065.9282785060.

The spelling of 1211111009 in words is "one billion, two hundred eleven million, one hundred eleven thousand, nine".