78999961 has 2 divisors, whose sum is σ = 78999962. Its totient is φ = 78999960.

The previous prime is 78999959. The next prime is 78999979. The reversal of 78999961 is 16999987.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42771600 + 36228361 = 6540^2 + 6019^2 .

It is a cyclic number.

It is not a de Polignac number, because 78999961 - 2¹ = 78999959 is a prime.

Together with 78999959, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 78999896 and 78999905.

It is not a weakly prime, because it can be changed into another prime (78999911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39499980 + 39499981.

It is an arithmetic number, because the mean of its divisors is an integer number (39499981).

Almost surely, 2^78999961 is an apocalyptic number.

It is an amenable number.

78999961 is a deficient number, since it is larger than the sum of its proper divisors (1).

78999961 is an equidigital number, since it uses as much as digits as its factorization.

78999961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2204496, while the sum is 58.

The square root of 78999961 is about 8888.1922233939. The cubic root of 78999961 is about 429.0839720938.

The spelling of 78999961 in words is "seventy-eight million, nine hundred ninety-nine thousand, nine hundred sixty-one".