7978645 has 4 divisors (see below), whose sum is σ = 9574380. Its totient is φ = 6382912.

The previous prime is 7978639. The next prime is 7978657. The reversal of 7978645 is 5468797.

It is a happy number.

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 1633284 + 6345361 = 1278^2 + 2519^2 .

It is a cyclic number.

It is not a de Polignac number, because 7978645 - 2³ = 7978637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 7978595 and 7978604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 797860 + ... + 797869.

It is an arithmetic number, because the mean of its divisors is an integer number (2393595).

Almost surely, 2^7978645 is an apocalyptic number.

It is an amenable number.

7978645 is a deficient number, since it is larger than the sum of its proper divisors (1595735).

7978645 is a wasteful number, since it uses less digits than its factorization.

7978645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1595734.

The product of its digits is 423360, while the sum is 46.

The square root of 7978645 is about 2824.6495357832. The cubic root of 7978645 is about 199.8218830856.

The spelling of 7978645 in words is "seven million, nine hundred seventy-eight thousand, six hundred forty-five".