78127891 has 2 divisors, whose sum is σ = 78127892. Its totient is φ = 78127890.

The previous prime is 78127823. The next prime is 78127901. The reversal of 78127891 is 19872187.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78127891 - 2¹¹ = 78125843 is a prime.

It is a super-2 number, since 2×78127891² = 12207934704215762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78127811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39063945 + 39063946.

It is an arithmetic number, because the mean of its divisors is an integer number (39063946).

Almost surely, 2^78127891 is an apocalyptic number.

78127891 is a deficient number, since it is larger than the sum of its proper divisors (1).

78127891 is an equidigital number, since it uses as much as digits as its factorization.

78127891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 56448, while the sum is 43.

The square root of 78127891 is about 8838.9983029753. The cubic root of 78127891 is about 427.4992597140.

The spelling of 78127891 in words is "seventy-eight million, one hundred twenty-seven thousand, eight hundred ninety-one".