661078791 has 12 divisors (see below), whose sum is σ = 955406400. Its totient is φ = 440481600.

The previous prime is 661078783. The next prime is 661078807. The reversal of 661078791 is 197870166.

661078791 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661078791 - 2³ = 661078783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661078771) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1266 + ... + 36383.

It is an arithmetic number, because the mean of its divisors is an integer number (79617200).

Almost surely, 2^661078791 is an apocalyptic number.

661078791 is a deficient number, since it is larger than the sum of its proper divisors (294327609).

661078791 is a wasteful number, since it uses less digits than its factorization.

661078791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39606 (or 39603 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The square root of 661078791 is about 25711.4525260632. The cubic root of 661078791 is about 871.1328840461.

The spelling of 661078791 in words is "six hundred sixty-one million, seventy-eight thousand, seven hundred ninety-one".