1206055561 has 4 divisors (see below), whose sum is σ = 1215262224. Its totient is φ = 1196848900.

The previous prime is 1206055559. The next prime is 1206055597. The reversal of 1206055561 is 1655506021.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1206055561 - 2¹ = 1206055559 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1206050561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4603135 + ... + 4603396.

It is an arithmetic number, because the mean of its divisors is an integer number (303815556).

Almost surely, 2^1206055561 is an apocalyptic number.

It is an amenable number.

1206055561 is a deficient number, since it is larger than the sum of its proper divisors (9206663).

1206055561 is an equidigital number, since it uses as much as digits as its factorization.

1206055561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9206662.

The product of its (nonzero) digits is 9000, while the sum is 31.

The square root of 1206055561 is about 34728.3106557172. The cubic root of 1206055561 is about 1064.4430691068.

The spelling of 1206055561 in words is "one billion, two hundred six million, fifty-five thousand, five hundred sixty-one".