61856585309 has 2 divisors, whose sum is σ = 61856585310. Its totient is φ = 61856585308.

The previous prime is 61856585303. The next prime is 61856585333. The reversal of 61856585309 is 90358565816.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50871449209 + 10985136100 = 225547^2 + 104810^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61856585309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61856585303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30928292654 + 30928292655.

It is an arithmetic number, because the mean of its divisors is an integer number (30928292655).

Almost surely, 2^61856585309 is an apocalyptic number.

It is an amenable number.

61856585309 is a deficient number, since it is larger than the sum of its proper divisors (1).

61856585309 is an equidigital number, since it uses as much as digits as its factorization.

61856585309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776000, while the sum is 56.

The spelling of 61856585309 in words is "sixty-one billion, eight hundred fifty-six million, five hundred eighty-five thousand, three hundred nine".