780975661 has 2 divisors, whose sum is σ = 780975662. Its totient is φ = 780975660.

The previous prime is 780975551. The next prime is 780975721. The reversal of 780975661 is 166579087.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 596287561 + 184688100 = 24419^2 + 13590^2 .

It is a cyclic number.

It is not a de Polignac number, because 780975661 - 2¹⁵ = 780942893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (780975061) 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, 390487830 + 390487831.

It is an arithmetic number, because the mean of its divisors is an integer number (390487831).

Almost surely, 2^780975661 is an apocalyptic number.

It is an amenable number.

780975661 is a deficient number, since it is larger than the sum of its proper divisors (1).

780975661 is an equidigital number, since it uses as much as digits as its factorization.

780975661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 635040, while the sum is 49.

The square root of 780975661 is about 27945.9417626245. The cubic root of 780975661 is about 920.9000568637.

The spelling of 780975661 in words is "seven hundred eighty million, nine hundred seventy-five thousand, six hundred sixty-one".