78398251 has 2 divisors, whose sum is σ = 78398252. Its totient is φ = 78398250.

The previous prime is 78398249. The next prime is 78398263. The reversal of 78398251 is 15289387.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78398251 - 2¹ = 78398249 is a prime.

It is a super-2 number, since 2×78398251² = 12292571519718002, which contains 22 as substring.

Together with 78398249, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 78398198 and 78398207.

It is not a weakly prime, because it can be changed into another prime (78398851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39199125 + 39199126.

It is an arithmetic number, because the mean of its divisors is an integer number (39199126).

Almost surely, 2^78398251 is an apocalyptic number.

78398251 is a deficient number, since it is larger than the sum of its proper divisors (1).

78398251 is an equidigital number, since it uses as much as digits as its factorization.

78398251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 43.

The square root of 78398251 is about 8854.2786832130. The cubic root of 78398251 is about 427.9918095355.

The spelling of 78398251 in words is "seventy-eight million, three hundred ninety-eight thousand, two hundred fifty-one".