78906217 has 4 divisors (see below), whose sum is σ = 84975940. Its totient is φ = 72836496.

The previous prime is 78906203. The next prime is 78906251. The reversal of 78906217 is 71260987.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16353936 + 62552281 = 4044^2 + 7909^2 .

It is a cyclic number.

It is not a de Polignac number, because 78906217 - 2¹⁵ = 78873449 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78906217.

It is not an unprimeable number, because it can be changed into a prime (78906277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3034842 + ... + 3034867.

It is an arithmetic number, because the mean of its divisors is an integer number (21243985).

Almost surely, 2^78906217 is an apocalyptic number.

It is an amenable number.

78906217 is a deficient number, since it is larger than the sum of its proper divisors (6069723).

78906217 is a wasteful number, since it uses less digits than its factorization.

78906217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6069722.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 78906217 is about 8882.9171447222. The cubic root of 78906217 is about 428.9141831122.

The spelling of 78906217 in words is "seventy-eight million, nine hundred six thousand, two hundred seventeen".