7978681 has 4 divisors (see below), whose sum is σ = 8088052. Its totient is φ = 7869312.

The previous prime is 7978679. The next prime is 7978699. The reversal of 7978681 is 1868797.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1868797 = 7 ⋅266971.

It can be written as a sum of positive squares in 2 ways, for example, as 2295225 + 5683456 = 1515^2 + 2384^2 .

It is a cyclic number.

It is not a de Polignac number, because 7978681 - 2¹ = 7978679 is a prime.

It is a super-2 number, since 2×7978681² = 127318700999522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7978181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54576 + ... + 54721.

It is an arithmetic number, because the mean of its divisors is an integer number (2022013).

Almost surely, 2^7978681 is an apocalyptic number.

It is an amenable number.

7978681 is a deficient number, since it is larger than the sum of its proper divisors (109371).

7978681 is a wasteful number, since it uses less digits than its factorization.

7978681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 109370.

The product of its digits is 169344, while the sum is 46.

The square root of 7978681 is about 2824.6559082479. The cubic root of 7978681 is about 199.8221836202.

The spelling of 7978681 in words is "seven million, nine hundred seventy-eight thousand, six hundred eighty-one".