1221397 has 4 divisors (see below), whose sum is σ = 1226176. Its totient is φ = 1216620.

The previous prime is 1221391. The next prime is 1221421. The reversal of 1221397 is 7931221.

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, and also an emirpimes, since its reverse is a distinct semiprime: 7931221 = 43 ⋅184447.

It is a cyclic number.

It is not a de Polignac number, because 1221397 - 2¹¹ = 1219349 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 (1221391) 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, 1983 + ... + 2524.

It is an arithmetic number, because the mean of its divisors is an integer number (306544).

2^1221397 is an apocalyptic number.

It is an amenable number.

1221397 is a deficient number, since it is larger than the sum of its proper divisors (4779).

1221397 is an equidigital number, since it uses as much as digits as its factorization.

1221397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4778.

The product of its digits is 756, while the sum is 25.

The square root of 1221397 is about 1105.1683129732. The cubic root of 1221397 is about 106.8937425949.

The spelling of 1221397 in words is "one million, two hundred twenty-one thousand, three hundred ninety-seven".