1220551 has 4 divisors (see below), whose sum is σ = 1233232. Its totient is φ = 1207872.

The previous prime is 1220507. The next prime is 1220591. The reversal of 1220551 is 1550221.

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

It is a cyclic number.

It is not a de Polignac number, because 1220551 - 2⁷ = 1220423 is a prime.

It is a Duffinian number.

1220551 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220591) 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, 6195 + ... + 6388.

It is an arithmetic number, because the mean of its divisors is an integer number (308308).

2^1220551 is an apocalyptic number.

1220551 is a deficient number, since it is larger than the sum of its proper divisors (12681).

1220551 is an equidigital number, since it uses as much as digits as its factorization.

1220551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12680.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 1220551 is about 1104.7854995428. The cubic root of 1220551 is about 106.8690569293.

Adding to 1220551 its reverse (1550221), we get a palindrome (2770772).

It can be divided in two parts, 1220 and 551, that multiplied together give a triangular number (672220 = T₁₁₅₉).

The spelling of 1220551 in words is "one million, two hundred twenty thousand, five hundred fifty-one".