61042721 has 2 divisors, whose sum is σ = 61042722. Its totient is φ = 61042720.

The previous prime is 61042703. The next prime is 61042753. The reversal of 61042721 is 12724016.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30913600 + 30129121 = 5560^2 + 5489^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61042721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (61042771) 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, 30521360 + 30521361.

It is an arithmetic number, because the mean of its divisors is an integer number (30521361).

Almost surely, 2^61042721 is an apocalyptic number.

It is an amenable number.

61042721 is a deficient number, since it is larger than the sum of its proper divisors (1).

61042721 is an equidigital number, since it uses as much as digits as its factorization.

61042721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 61042721 is about 7812.9841289996. The cubic root of 61042721 is about 393.7415936393.

Adding to 61042721 its reverse (12724016), we get a palindrome (73766737).

The spelling of 61042721 in words is "sixty-one million, forty-two thousand, seven hundred twenty-one".