7661778 has 16 divisors (see below), whose sum is σ = 15370560. Its totient is φ = 2546096.

The previous prime is 7661777. The next prime is 7661789. The reversal of 7661778 is 8771667.

7661778 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (7661777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 376 + ... + 3932.

It is an arithmetic number, because the mean of its divisors is an integer number (960660).

Almost surely, 2^7661778 is an apocalyptic number.

7661778 is an abundant number, since it is smaller than the sum of its proper divisors (7708782).

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

7661778 is a wasteful number, since it uses less digits than its factorization.

7661778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3921.

The product of its digits is 98784, while the sum is 42.

The square root of 7661778 is about 2767.9916907390. The cubic root of 7661778 is about 197.1408030812.

The spelling of 7661778 in words is "seven million, six hundred sixty-one thousand, seven hundred seventy-eight".