61781789 has 2 divisors, whose sum is σ = 61781790. Its totient is φ = 61781788.

The previous prime is 61781779. The next prime is 61781813. The reversal of 61781789 is 98718716.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 53772889 + 8008900 = 7333^2 + 2830^2 .

It is a cyclic number.

It is not a de Polignac number, because 61781789 - 2⁴ = 61781773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61781779) 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, 30890894 + 30890895.

It is an arithmetic number, because the mean of its divisors is an integer number (30890895).

Almost surely, 2^61781789 is an apocalyptic number.

It is an amenable number.

61781789 is a deficient number, since it is larger than the sum of its proper divisors (1).

61781789 is an equidigital number, since it uses as much as digits as its factorization.

61781789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 47.

The square root of 61781789 is about 7860.1392481304. The cubic root of 61781789 is about 395.3242842514.

The spelling of 61781789 in words is "sixty-one million, seven hundred eighty-one thousand, seven hundred eighty-nine".