1221491 has 8 divisors (see below), whose sum is σ = 1311120. Its totient is φ = 1134432.

The previous prime is 1221469. The next prime is 1221499. The reversal of 1221491 is 1941221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1221491 - 2⁶ = 1221427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 401 + ... + 1613.

It is an arithmetic number, because the mean of its divisors is an integer number (163890).

2^1221491 is an apocalyptic number.

1221491 is a deficient number, since it is larger than the sum of its proper divisors (89629).

1221491 is a wasteful number, since it uses less digits than its factorization.

1221491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1285.

The product of its digits is 144, while the sum is 20.

The square root of 1221491 is about 1105.2108396139. The cubic root of 1221491 is about 106.8964847429.

The spelling of 1221491 in words is "one million, two hundred twenty-one thousand, four hundred ninety-one".