777779960921 has 2 divisors, whose sum is σ = 777779960922. Its totient is φ = 777779960920.

The previous prime is 777779960891. The next prime is 777779960981. The reversal of 777779960921 is 129069977777.

777779960921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 669673808896 + 108106152025 = 818336^2 + 328795^2 .

It is a cyclic number.

It is not a de Polignac number, because 777779960921 - 2¹⁴ = 777779944537 is a prime.

It is a super-2 number, since 2×777779960921² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (777779960981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 388889980460 + 388889980461.

It is an arithmetic number, because the mean of its divisors is an integer number (388889980461).

Almost surely, 2^777779960921 is an apocalyptic number.

It is an amenable number.

777779960921 is a deficient number, since it is larger than the sum of its proper divisors (1).

777779960921 is an equidigital number, since it uses as much as digits as its factorization.

777779960921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 147027636, while the sum is 71.

The spelling of 777779960921 in words is "seven hundred seventy-seven billion, seven hundred seventy-nine million, nine hundred sixty thousand, nine hundred twenty-one".