78173661 has 16 divisors (see below), whose sum is σ = 107840000. Its totient is φ = 50319360.

The previous prime is 78173653. The next prime is 78173663. The reversal of 78173661 is 16637187.

It is not a de Polignac number, because 78173661 - 2³ = 78173653 is a prime.

It is a super-2 number, since 2×78173661² = 12222242548285842, which contains 22 as substring.

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78173663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 61965 + ... + 63213.

It is an arithmetic number, because the mean of its divisors is an integer number (6740000).

Almost surely, 2^78173661 is an apocalyptic number.

It is an amenable number.

78173661 is a deficient number, since it is larger than the sum of its proper divisors (29666339).

78173661 is a wasteful number, since it uses less digits than its factorization.

78173661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1956.

The product of its digits is 42336, while the sum is 39.

The square root of 78173661 is about 8841.5870181772. The cubic root of 78173661 is about 427.5827246634.

The spelling of 78173661 in words is "seventy-eight million, one hundred seventy-three thousand, six hundred sixty-one".