1223991 has 28 divisors (see below), whose sum is σ = 1941168. Its totient is φ = 769824.

The previous prime is 1223987. The next prime is 1223993. The reversal of 1223991 is 1993221.

It is not a de Polignac number, because 1223991 - 2² = 1223987 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 (1223993) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 16731 + ... + 16803.

2^1223991 is an apocalyptic number.

1223991 is a deficient number, since it is larger than the sum of its proper divisors (717177).

1223991 is an frugal number, since it uses more digits than its factorization.

1223991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114 (or 99 counting only the distinct ones).

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

The square root of 1223991 is about 1106.3412674216. The cubic root of 1223991 is about 106.9693626437.

The spelling of 1223991 in words is "one million, two hundred twenty-three thousand, nine hundred ninety-one".