7778407961 has 2 divisors, whose sum is σ = 7778407962. Its totient is φ = 7778407960.

The previous prime is 7778407951. The next prime is 7778407993. The reversal of 7778407961 is 1697048777.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6313891600 + 1464516361 = 79460^2 + 38269^2 .

It is an emirp because it is prime and its reverse (1697048777) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 7778407961 - 2²⁶ = 7711299097 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 7778407897 and 7778407906.

It is not a weakly prime, because it can be changed into another prime (7778407951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3889203980 + 3889203981.

It is an arithmetic number, because the mean of its divisors is an integer number (3889203981).

Almost surely, 2^7778407961 is an apocalyptic number.

It is an amenable number.

7778407961 is a deficient number, since it is larger than the sum of its proper divisors (1).

7778407961 is an equidigital number, since it uses as much as digits as its factorization.

7778407961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4148928, while the sum is 56.

The square root of 7778407961 is about 88195.2830994946. The cubic root of 7778407961 is about 1981.3608269981.

The spelling of 7778407961 in words is "seven billion, seven hundred seventy-eight million, four hundred seven thousand, nine hundred sixty-one".