781690061 has 2 divisors, whose sum is σ = 781690062. Its totient is φ = 781690060.

The previous prime is 781690003. The next prime is 781690087. The reversal of 781690061 is 160096187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 754545961 + 27144100 = 27469^2 + 5210^2 .

It is a cyclic number.

It is not a de Polignac number, because 781690061 - 2¹⁴ = 781673677 is a prime.

It is a super-2 number, since 2×781690061² = 1222078702932367442, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 781689997 and 781690024.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (781690561) 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, 390845030 + 390845031.

It is an arithmetic number, because the mean of its divisors is an integer number (390845031).

Almost surely, 2^781690061 is an apocalyptic number.

It is an amenable number.

781690061 is a deficient number, since it is larger than the sum of its proper divisors (1).

781690061 is an equidigital number, since it uses as much as digits as its factorization.

781690061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 781690061 is about 27958.7206610031. The cubic root of 781690061 is about 921.1807700505.

The spelling of 781690061 in words is "seven hundred eighty-one million, six hundred ninety thousand, sixty-one".