777661 has 2 divisors, whose sum is σ = 777662. Its totient is φ = 777660.

The previous prime is 777643. The next prime is 777671. The reversal of 777661 is 166777.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 755161 + 22500 = 869^2 + 150^2 .

It is a cyclic number.

It is not a de Polignac number, because 777661 - 2¹¹ = 775613 is a prime.

It is an Ulam number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (777641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 388830 + 388831.

It is an arithmetic number, because the mean of its divisors is an integer number (388831).

2⁷⁷⁷⁶⁶¹ is an apocalyptic number.

It is an amenable number.

777661 is a deficient number, since it is larger than the sum of its proper divisors (1).

777661 is an equidigital number, since it uses as much as digits as its factorization.

777661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12348, while the sum is 34.

The square root of 777661 is about 881.8508944260. The cubic root of 777661 is about 91.9595363961.

The spelling of 777661 in words is "seven hundred seventy-seven thousand, six hundred sixty-one".