1201211821 has 2 divisors, whose sum is σ = 1201211822. Its totient is φ = 1201211820.

The previous prime is 1201211783. The next prime is 1201211873. The reversal of 1201211821 is 1281121021.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 832034025 + 369177796 = 28845^2 + 19214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1201211821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1201211021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 600605910 + 600605911.

It is an arithmetic number, because the mean of its divisors is an integer number (600605911).

Almost surely, 2^1201211821 is an apocalyptic number.

It is an amenable number.

1201211821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1201211821 is an equidigital number, since it uses as much as digits as its factorization.

1201211821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 19.

The square root of 1201211821 is about 34658.5028672619. The cubic root of 1201211821 is about 1063.0161577198.

Adding to 1201211821 its reverse (1281121021), we get a palindrome (2482332842).

The spelling of 1201211821 in words is "one billion, two hundred one million, two hundred eleven thousand, eight hundred twenty-one".