1221865 has 8 divisors (see below), whose sum is σ = 1513728. Its totient is φ = 945840.

The previous prime is 1221863. The next prime is 1221907. The reversal of 1221865 is 5681221.

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

It is not a de Polignac number, because 1221865 - 2¹ = 1221863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3787 + ... + 4096.

It is an arithmetic number, because the mean of its divisors is an integer number (189216).

2^1221865 is an apocalyptic number.

It is an amenable number.

1221865 is a deficient number, since it is larger than the sum of its proper divisors (291863).

1221865 is an equidigital number, since it uses as much as digits as its factorization.

1221865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7919.

The product of its digits is 960, while the sum is 25.

The square root of 1221865 is about 1105.3800251497. The cubic root of 1221865 is about 106.9073935981.

The spelling of 1221865 in words is "one million, two hundred twenty-one thousand, eight hundred sixty-five".