1221399 has 20 divisors (see below), whose sum is σ = 1934064. Its totient is φ = 765504.

The previous prime is 1221391. The next prime is 1221421. The reversal of 1221399 is 9931221.

It is not a de Polignac number, because 1221399 - 2³ = 1221391 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

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 19 ways as a sum of consecutive naturals, for example, 934 + ... + 1820.

2^1221399 is an apocalyptic number.

1221399 is a deficient number, since it is larger than the sum of its proper divisors (712665).

1221399 is an equidigital number, since it uses as much as digits as its factorization.

1221399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 916 (or 907 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 1221399 is about 1105.1692178124. The cubic root of 1221399 is about 106.8938009399.

It can be divided in two parts, 122 and 1399, that added together give a square (1521 = 39²).

The spelling of 1221399 in words is "one million, two hundred twenty-one thousand, three hundred ninety-nine".