61809906857 has 2 divisors, whose sum is σ = 61809906858. Its totient is φ = 61809906856.

The previous prime is 61809906839. The next prime is 61809906877. The reversal of 61809906857 is 75860990816.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38396010601 + 23413896256 = 195949^2 + 153016^2 .

It is a cyclic number.

It is not a de Polignac number, because 61809906857 - 2¹⁶ = 61809841321 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 61809906796 and 61809906805.

It is not a weakly prime, because it can be changed into another prime (61809906877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30904953428 + 30904953429.

It is an arithmetic number, because the mean of its divisors is an integer number (30904953429).

Almost surely, 2^61809906857 is an apocalyptic number.

It is an amenable number.

61809906857 is a deficient number, since it is larger than the sum of its proper divisors (1).

61809906857 is an equidigital number, since it uses as much as digits as its factorization.

61809906857 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6531840, while the sum is 59.

The spelling of 61809906857 in words is "sixty-one billion, eight hundred nine million, nine hundred six thousand, eight hundred fifty-seven".