691813947 has 8 divisors (see below), whose sum is σ = 1006274880. Its totient is φ = 419281160.

The previous prime is 691813939. The next prime is 691813961. The reversal of 691813947 is 749318196.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 691813947 - 2³ = 691813939 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 691813896 and 691813905.

It is not an unprimeable number, because it can be changed into a prime (691813247) 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 7 ways as a sum of consecutive naturals, for example, 10481997 + ... + 10482062.

It is an arithmetic number, because the mean of its divisors is an integer number (125784360).

Almost surely, 2^691813947 is an apocalyptic number.

691813947 is a deficient number, since it is larger than the sum of its proper divisors (314460933).

691813947 is a wasteful number, since it uses less digits than its factorization.

691813947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20964073.

The product of its digits is 326592, while the sum is 48.

The square root of 691813947 is about 26302.3563012898. The cubic root of 691813947 is about 884.4292646214.

The spelling of 691813947 in words is "six hundred ninety-one million, eight hundred thirteen thousand, nine hundred forty-seven".