55987781 has 2 divisors, whose sum is σ = 55987782. Its totient is φ = 55987780.

The previous prime is 55987759. The next prime is 55987807. The reversal of 55987781 is 18778955.

55987781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44488900 + 11498881 = 6670^2 + 3391^2 .

It is a cyclic number.

It is not a de Polignac number, because 55987781 - 2¹⁰ = 55986757 is a prime.

It is a super-2 number, since 2×55987781² = 6269263242607922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55987751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27993890 + 27993891.

It is an arithmetic number, because the mean of its divisors is an integer number (27993891).

Almost surely, 2^55987781 is an apocalyptic number.

It is an amenable number.

55987781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55987781 is an equidigital number, since it uses as much as digits as its factorization.

55987781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 705600, while the sum is 50.

The square root of 55987781 is about 7482.4983127295. The cubic root of 55987781 is about 382.5584082136.

The spelling of 55987781 in words is "fifty-five million, nine hundred eighty-seven thousand, seven hundred eighty-one".