1221211001 has 8 divisors (see below), whose sum is σ = 1255269960. Its totient is φ = 1187560192.

The previous prime is 1221210989. The next prime is 1221211021. The reversal of 1221211001 is 1001121221.

It can be written as a sum of positive squares in 4 ways, for example, as 34339600 + 1186871401 = 5860^2 + 34451^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221211001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221211021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 95966 + ... + 107943.

It is an arithmetic number, because the mean of its divisors is an integer number (156908745).

Almost surely, 2^1221211001 is an apocalyptic number.

It is an amenable number.

1221211001 is a deficient number, since it is larger than the sum of its proper divisors (34058959).

1221211001 is a wasteful number, since it uses less digits than its factorization.

1221211001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204075.

The product of its (nonzero) digits is 8, while the sum is 11.

The square root of 1221211001 is about 34945.8295222763. The cubic root of 1221211001 is about 1068.8831625694.

Adding to 1221211001 its reverse (1001121221), we get a palindrome (2222332222).

The spelling of 1221211001 in words is "one billion, two hundred twenty-one million, two hundred eleven thousand, one".