1221647 has 8 divisors (see below), whose sum is σ = 1419552. Its totient is φ = 1029600.

The previous prime is 1221641. The next prime is 1221653. The reversal of 1221647 is 7461221.

It is an interprime number because it is at equal distance from previous prime (1221641) and next prime (1221653).

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 1221647 - 2⁴ = 1221631 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221641) 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, 1004 + ... + 1857.

It is an arithmetic number, because the mean of its divisors is an integer number (177444).

2^1221647 is an apocalyptic number.

1221647 is a deficient number, since it is larger than the sum of its proper divisors (197905).

1221647 is an equidigital number, since it uses as much as digits as its factorization.

1221647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2929.

The product of its digits is 672, while the sum is 23.

The square root of 1221647 is about 1105.2814121300. The cubic root of 1221647 is about 106.9010352312.

Adding to 1221647 its reverse (7461221), we get a palindrome (8682868).

It can be divided in two parts, 1221 and 647, that multiplied together give a palindrome (789987).

The spelling of 1221647 in words is "one million, two hundred twenty-one thousand, six hundred forty-seven".