72778 has 4 divisors (see below), whose sum is σ = 109170. Its totient is φ = 36388.

The previous prime is 72767. The next prime is 72797. The reversal of 72778 is 87727.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 87727 = 37 ⋅2371.

It can be written as a sum of positive squares in only one way, i.e., 42849 + 29929 = 207^2 + 173^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

72778 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 18193 + ... + 18196.

2⁷²⁷⁷⁸ is an apocalyptic number.

72778 is a deficient number, since it is larger than the sum of its proper divisors (36392).

72778 is a wasteful number, since it uses less digits than its factorization.

72778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36391.

The product of its digits is 5488, while the sum is 31.

The square root of 72778 is about 269.7739794717. The cubic root of 72778 is about 41.7509830407.

The spelling of 72778 in words is "seventy-two thousand, seven hundred seventy-eight".