1220455561 has 8 divisors (see below), whose sum is σ = 1318129344. Its totient is φ = 1123323600.

The previous prime is 1220455553. The next prime is 1220455583. The reversal of 1220455561 is 1655540221.

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 1220455561 - 2³ = 1220455553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1220455501) 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, 130765 + ... + 139786.

It is an arithmetic number, because the mean of its divisors is an integer number (164766168).

Almost surely, 2^1220455561 is an apocalyptic number.

It is an amenable number.

1220455561 is a deficient number, since it is larger than the sum of its proper divisors (97673783).

1220455561 is a wasteful number, since it uses less digits than its factorization.

1220455561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 270911.

The product of its (nonzero) digits is 12000, while the sum is 31.

The square root of 1220455561 is about 34935.0191212199. The cubic root of 1220455561 is about 1068.6627137268.

Adding to 1220455561 its reverse (1655540221), we get a palindrome (2875995782).

The spelling of 1220455561 in words is "one billion, two hundred twenty million, four hundred fifty-five thousand, five hundred sixty-one".