1211644221 has 4 divisors (see below), whose sum is σ = 1615525632. Its totient is φ = 807762812.

The previous prime is 1211644219. The next prime is 1211644223. The reversal of 1211644221 is 1224461121.

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 an interprime number because it is at equal distance from previous prime (1211644219) and next prime (1211644223).

It is a cyclic number.

It is not a de Polignac number, because 1211644221 - 2¹ = 1211644219 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1211644191 and 1211644200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211644223) 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, 201940701 + ... + 201940706.

It is an arithmetic number, because the mean of its divisors is an integer number (403881408).

Almost surely, 2^1211644221 is an apocalyptic number.

It is an amenable number.

1211644221 is a deficient number, since it is larger than the sum of its proper divisors (403881411).

1211644221 is an equidigital number, since it uses as much as digits as its factorization.

1211644221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403881410.

The product of its digits is 768, while the sum is 24.

The square root of 1211644221 is about 34808.6802536379. The cubic root of 1211644221 is about 1066.0846865079.

The spelling of 1211644221 in words is "one billion, two hundred eleven million, six hundred forty-four thousand, two hundred twenty-one".