55491561 has 10 divisors (see below), whose sum is σ = 82894922. Its totient is φ = 36994320.

The previous prime is 55491539. The next prime is 55491577. The reversal of 55491561 is 16519455.

55491561 is a `hidden beast` number, since 5 + 5 + 4 + 91 + 561 = 666.

It can be written as a sum of positive squares in only one way, i.e., 47403225 + 8088336 = 6885^2 + 2844^2 .

It is not a de Polignac number, because 55491561 - 2⁶ = 55491497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (55491661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 342460 + ... + 342621.

Almost surely, 2^55491561 is an apocalyptic number.

It is an amenable number.

55491561 is a deficient number, since it is larger than the sum of its proper divisors (27403361).

55491561 is an equidigital number, since it uses as much as digits as its factorization.

55491561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 685093 (or 685084 counting only the distinct ones).

The product of its digits is 27000, while the sum is 36.

The square root of 55491561 is about 7449.2658027486. The cubic root of 55491561 is about 381.4248469346.

The spelling of 55491561 in words is "fifty-five million, four hundred ninety-one thousand, five hundred sixty-one".