55393781 has 2 divisors, whose sum is σ = 55393782. Its totient is φ = 55393780.

The previous prime is 55393771. The next prime is 55393813. The reversal of 55393781 is 18739355.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 32878756 + 22515025 = 5734^2 + 4745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55393781 is a prime.

It is a super-2 number, since 2×55393781² = 6136941946951922, 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 (55393711) 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 as a sum of consecutive naturals, namely, 27696890 + 27696891.

It is an arithmetic number, because the mean of its divisors is an integer number (27696891).

Almost surely, 2^55393781 is an apocalyptic number.

It is an amenable number.

55393781 is a deficient number, since it is larger than the sum of its proper divisors (1).

55393781 is an equidigital number, since it uses as much as digits as its factorization.

55393781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 113400, while the sum is 41.

The square root of 55393781 is about 7442.6998461580. The cubic root of 55393781 is about 381.2006828262.

The spelling of 55393781 in words is "fifty-five million, three hundred ninety-three thousand, seven hundred eighty-one".