55740721 has 2 divisors, whose sum is σ = 55740722. Its totient is φ = 55740720.

The previous prime is 55740691. The next prime is 55740743. The reversal of 55740721 is 12704755.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51480625 + 4260096 = 7175^2 + 2064^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55740721 is a prime.

It is not a weakly prime, because it can be changed into another prime (55740521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27870360 + 27870361.

It is an arithmetic number, because the mean of its divisors is an integer number (27870361).

Almost surely, 2^55740721 is an apocalyptic number.

It is an amenable number.

55740721 is a deficient number, since it is larger than the sum of its proper divisors (1).

55740721 is an equidigital number, since it uses as much as digits as its factorization.

55740721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9800, while the sum is 31.

The square root of 55740721 is about 7465.9708678778. The cubic root of 55740721 is about 381.9948671222.

The spelling of 55740721 in words is "fifty-five million, seven hundred forty thousand, seven hundred twenty-one".