55505581 has 2 divisors, whose sum is σ = 55505582. Its totient is φ = 55505580.

The previous prime is 55505557. The next prime is 55505591. The reversal of 55505581 is 18550555.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29800681 + 25704900 = 5459^2 + 5070^2 .

It is a cyclic number.

It is not a de Polignac number, because 55505581 - 2¹¹ = 55503533 is a prime.

It is a super-2 number, since 2×55505581² = 6161739044295122, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55505521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27752790 + 27752791.

It is an arithmetic number, because the mean of its divisors is an integer number (27752791).

Almost surely, 2^55505581 is an apocalyptic number.

It is an amenable number.

55505581 is a deficient number, since it is larger than the sum of its proper divisors (1).

55505581 is an equidigital number, since it uses as much as digits as its factorization.

55505581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25000, while the sum is 34.

The square root of 55505581 is about 7450.2067756539. The cubic root of 55505581 is about 381.4569666898.

The spelling of 55505581 in words is "fifty-five million, five hundred five thousand, five hundred eighty-one".