78205665 has 16 divisors (see below), whose sum is σ = 125496000. Its totient is φ = 41587392.

The previous prime is 78205657. The next prime is 78205667. The reversal of 78205665 is 56650287.

It is a happy number.

It is not a de Polignac number, because 78205665 - 2³ = 78205657 is a prime.

It is a super-2 number, since 2×78205665² = 12232252076184450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78205667) 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, 2235 + ... + 12704.

It is an arithmetic number, because the mean of its divisors is an integer number (7843500).

Almost surely, 2^78205665 is an apocalyptic number.

It is an amenable number.

78205665 is a deficient number, since it is larger than the sum of its proper divisors (47290335).

78205665 is a wasteful number, since it uses less digits than its factorization.

78205665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15296.

The product of its (nonzero) digits is 100800, while the sum is 39.

The square root of 78205665 is about 8843.3966890556. The cubic root of 78205665 is about 427.6410669505.

The spelling of 78205665 in words is "seventy-eight million, two hundred five thousand, six hundred sixty-five".