1221845 has 8 divisors (see below), whose sum is σ = 1500576. Its totient is φ = 954576.

The previous prime is 1221823. The next prime is 1221853. The reversal of 1221845 is 5481221.

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 1221845 - 2⁸ = 1221589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221845.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2627 + ... + 3056.

It is an arithmetic number, because the mean of its divisors is an integer number (187572).

2^1221845 is an apocalyptic number.

It is an amenable number.

1221845 is a deficient number, since it is larger than the sum of its proper divisors (278731).

1221845 is an equidigital number, since it uses as much as digits as its factorization.

1221845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5731.

The product of its digits is 640, while the sum is 23.

The square root of 1221845 is about 1105.3709784502. The cubic root of 1221845 is about 106.9068102932.

The spelling of 1221845 in words is "one million, two hundred twenty-one thousand, eight hundred forty-five".