91720779 has 8 divisors (see below), whose sum is σ = 123482112. Its totient is φ = 60553320.

The previous prime is 91720747. The next prime is 91720787. The reversal of 91720779 is 97702719.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91720779 - 2⁵ = 91720747 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91720779.

It is not an unprimeable number, because it can be changed into a prime (91720379) 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, 148107 + ... + 148724.

It is an arithmetic number, because the mean of its divisors is an integer number (15435264).

Almost surely, 2^91720779 is an apocalyptic number.

91720779 is a deficient number, since it is larger than the sum of its proper divisors (31761333).

91720779 is a wasteful number, since it uses less digits than its factorization.

91720779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296937.

The product of its (nonzero) digits is 55566, while the sum is 42.

The square root of 91720779 is about 9577.0965850826. The cubic root of 91720779 is about 450.9785766033.

The spelling of 91720779 in words is "ninety-one million, seven hundred twenty thousand, seven hundred seventy-nine".