691638893 has 16 divisors (see below), whose sum is σ = 821620800. Its totient is φ = 575124480.

The previous prime is 691638877. The next prime is 691638907. The reversal of 691638893 is 398836196.

691638893 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 691638893 - 2⁴ = 691638877 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691638593) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 50996 + ... + 63117.

It is an arithmetic number, because the mean of its divisors is an integer number (51351300).

Almost surely, 2^691638893 is an apocalyptic number.

It is an amenable number.

691638893 is a deficient number, since it is larger than the sum of its proper divisors (129981907).

691638893 is a wasteful number, since it uses less digits than its factorization.

691638893 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 114172.

The product of its digits is 1679616, while the sum is 53.

The square root of 691638893 is about 26299.0283660823. The cubic root of 691638893 is about 884.3546607766.

The spelling of 691638893 in words is "six hundred ninety-one million, six hundred thirty-eight thousand, eight hundred ninety-three".