55561691 has 2 divisors, whose sum is σ = 55561692. Its totient is φ = 55561690.

The previous prime is 55561669. The next prime is 55561699. The reversal of 55561691 is 19616555.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55561691 is a prime.

It is not a weakly prime, because it can be changed into another prime (55561699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27780845 + 27780846.

It is an arithmetic number, because the mean of its divisors is an integer number (27780846).

Almost surely, 2^55561691 is an apocalyptic number.

55561691 is a deficient number, since it is larger than the sum of its proper divisors (1).

55561691 is an equidigital number, since it uses as much as digits as its factorization.

55561691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40500, while the sum is 38.

The square root of 55561691 is about 7453.9714917620. The cubic root of 55561691 is about 381.5854603287.

The spelling of 55561691 in words is "fifty-five million, five hundred sixty-one thousand, six hundred ninety-one".