7720978 has 4 divisors (see below), whose sum is σ = 11581470. Its totient is φ = 3860488.

The previous prime is 7720969. The next prime is 7721003. The reversal of 7720978 is 8790277.

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

It can be written as a sum of positive squares in only one way, i.e., 7327849 + 393129 = 2707^2 + 627^2 .

It is a super-2 number, since 2×7720978² = 119227002552968, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 7720978.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1930243 + ... + 1930246.

Almost surely, 2^7720978 is an apocalyptic number.

7720978 is a deficient number, since it is larger than the sum of its proper divisors (3860492).

7720978 is a wasteful number, since it uses less digits than its factorization.

7720978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3860491.

The product of its (nonzero) digits is 49392, while the sum is 40.

The square root of 7720978 is about 2778.6647872674. The cubic root of 7720978 is about 197.6472479858.

The spelling of 7720978 in words is "seven million, seven hundred twenty thousand, nine hundred seventy-eight".