78166399 has 4 divisors (see below), whose sum is σ = 82280440. Its totient is φ = 74052360.

The previous prime is 78166381. The next prime is 78166409. The reversal of 78166399 is 99366187.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99366187 = 23 ⋅4320269.

It is a cyclic number.

It is not a de Polignac number, because 78166399 - 2⁵ = 78166367 is a prime.

It is a super-2 number, since 2×78166399² = 12219971865254402, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78166379) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2056992 + ... + 2057029.

It is an arithmetic number, because the mean of its divisors is an integer number (20570110).

Almost surely, 2^78166399 is an apocalyptic number.

78166399 is a deficient number, since it is larger than the sum of its proper divisors (4114041).

78166399 is a wasteful number, since it uses less digits than its factorization.

78166399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4114040.

The product of its digits is 489888, while the sum is 49.

The square root of 78166399 is about 8841.1763357599. The cubic root of 78166399 is about 427.5694840490.

The spelling of 78166399 in words is "seventy-eight million, one hundred sixty-six thousand, three hundred ninety-nine".