78815771 has 2 divisors, whose sum is σ = 78815772. Its totient is φ = 78815770.

The previous prime is 78815761. The next prime is 78815773. The reversal of 78815771 is 17751887.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78815771 - 2¹⁴ = 78799387 is a prime.

Together with 78815773, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78815773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39407885 + 39407886.

It is an arithmetic number, because the mean of its divisors is an integer number (39407886).

Almost surely, 2^78815771 is an apocalyptic number.

78815771 is a deficient number, since it is larger than the sum of its proper divisors (1).

78815771 is an equidigital number, since it uses as much as digits as its factorization.

78815771 is an evil number, because the sum of its binary digits is even.

The product of its digits is 109760, while the sum is 44.

The square root of 78815771 is about 8877.8246772506. The cubic root of 78815771 is about 428.7502399509.

The spelling of 78815771 in words is "seventy-eight million, eight hundred fifteen thousand, seven hundred seventy-one".