1221211837 has 4 divisors (see below), whose sum is σ = 1263322620. Its totient is φ = 1179101056.

The previous prime is 1221211801. The next prime is 1221211867. The reversal of 1221211837 is 7381121221.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1029832281 + 191379556 = 32091^2 + 13834^2 .

It is a cyclic number.

It is not a de Polignac number, because 1221211837 - 2⁷ = 1221211709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211867) 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, 21055348 + ... + 21055405.

It is an arithmetic number, because the mean of its divisors is an integer number (315830655).

Almost surely, 2^1221211837 is an apocalyptic number.

It is an amenable number.

1221211837 is a deficient number, since it is larger than the sum of its proper divisors (42110783).

1221211837 is an equidigital number, since it uses as much as digits as its factorization.

1221211837 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42110782.

The product of its digits is 1344, while the sum is 28.

The square root of 1221211837 is about 34945.8414836444. The cubic root of 1221211837 is about 1068.8834064765.

The spelling of 1221211837 in words is "one billion, two hundred twenty-one million, two hundred eleven thousand, eight hundred thirty-seven".