7977640 has 32 divisors (see below), whose sum is σ = 19582560. Its totient is φ = 2900800.

The previous prime is 7977617. The next prime is 7977643. The reversal of 7977640 is 467797.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 7977593 and 7977602.

It is not an unprimeable number, because it can be changed into a prime (7977643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8626 + ... + 9505.

It is an arithmetic number, because the mean of its divisors is an integer number (611955).

Almost surely, 2^7977640 is an apocalyptic number.

It is an amenable number.

7977640 is an abundant number, since it is smaller than the sum of its proper divisors (11604920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7977640 is a wasteful number, since it uses less digits than its factorization.

7977640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18153 (or 18149 counting only the distinct ones).

The product of its (nonzero) digits is 74088, while the sum is 40.

The square root of 7977640 is about 2824.4716320048. The cubic root of 7977640 is about 199.8134927960.

The spelling of 7977640 in words is "seven million, nine hundred seventy-seven thousand, six hundred forty".