691393779 has 32 divisors (see below), whose sum is σ = 1034880000. Its totient is φ = 456194592.

The previous prime is 691393739. The next prime is 691393789. The reversal of 691393779 is 977393196.

It is not a de Polignac number, because 691393779 - 2⁸ = 691393523 is a prime.

It is not an unprimeable number, because it can be changed into a prime (691393709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1980897 + ... + 1981245.

It is an arithmetic number, because the mean of its divisors is an integer number (32340000).

Almost surely, 2^691393779 is an apocalyptic number.

691393779 is a deficient number, since it is larger than the sum of its proper divisors (343486221).

691393779 is a wasteful number, since it uses less digits than its factorization.

691393779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 904 (or 898 counting only the distinct ones).

The product of its digits is 1928934, while the sum is 54.

The square root of 691393779 is about 26294.3678189836. The cubic root of 691393779 is about 884.2501778724.

The spelling of 691393779 in words is "six hundred ninety-one million, three hundred ninety-three thousand, seven hundred seventy-nine".