1221813 has 6 divisors (see below), whose sum is σ = 1764854. Its totient is φ = 814536.

The previous prime is 1221811. The next prime is 1221821. The reversal of 1221813 is 3181221.

It can be written as a sum of positive squares in only one way, i.e., 762129 + 459684 = 873^2 + 678^2 .

It is not a de Polignac number, because 1221813 - 2¹ = 1221811 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 (1221811) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 67870 + ... + 67887.

2^1221813 is an apocalyptic number.

It is an amenable number.

1221813 is a deficient number, since it is larger than the sum of its proper divisors (543041).

1221813 is a wasteful number, since it uses less digits than its factorization.

1221813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135763 (or 135760 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1221813 is about 1105.3565035770. The cubic root of 1221813 is about 106.9058769922.

The spelling of 1221813 in words is "one million, two hundred twenty-one thousand, eight hundred thirteen".