55078781 has 2 divisors, whose sum is σ = 55078782. Its totient is φ = 55078780.

The previous prime is 55078763. The next prime is 55078811. The reversal of 55078781 is 18787055.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 40896025 + 14182756 = 6395^2 + 3766^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55078781 is a prime.

It is a super-2 number, since 2×55078781² = 6067344232891922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55078711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27539390 + 27539391.

It is an arithmetic number, because the mean of its divisors is an integer number (27539391).

Almost surely, 2^55078781 is an apocalyptic number.

It is an amenable number.

55078781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55078781 is an equidigital number, since it uses as much as digits as its factorization.

55078781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 78400, while the sum is 41.

The square root of 55078781 is about 7421.5080003999. The cubic root of 55078781 is about 380.4767354483.

The spelling of 55078781 in words is "fifty-five million, seventy-eight thousand, seven hundred eighty-one".