1226991 has 4 divisors (see below), whose sum is σ = 1635992. Its totient is φ = 817992.

The previous prime is 1226983. The next prime is 1226993. The reversal of 1226991 is 1996221.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1226991 - 2³ = 1226983 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1226993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 204496 + ... + 204501.

It is an arithmetic number, because the mean of its divisors is an integer number (408998).

2^1226991 is an apocalyptic number.

1226991 is a deficient number, since it is larger than the sum of its proper divisors (409001).

1226991 is an equidigital number, since it uses as much as digits as its factorization.

1226991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409000.

The product of its digits is 1944, while the sum is 30.

The square root of 1226991 is about 1107.6962580058. The cubic root of 1226991 is about 107.0566852527.

Subtracting from 1226991 its sum of digits (30), we obtain a triangular number (1226961 = T₁₅₆₆).

The spelling of 1226991 in words is "one million, two hundred twenty-six thousand, nine hundred ninety-one".