691159649 has 4 divisors (see below), whose sum is σ = 691702164. Its totient is φ = 690617136.

The previous prime is 691159613. The next prime is 691159661. The reversal of 691159649 is 946951196.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 546390625 + 144769024 = 23375^2 + 12032^2 .

It is a cyclic number.

It is not a de Polignac number, because 691159649 - 2²⁴ = 674382433 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 691159597 and 691159606.

It is not an unprimeable number, because it can be changed into a prime (691159699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 269342 + ... + 271895.

It is an arithmetic number, because the mean of its divisors is an integer number (172925541).

Almost surely, 2^691159649 is an apocalyptic number.

It is an amenable number.

691159649 is a deficient number, since it is larger than the sum of its proper divisors (542515).

691159649 is a wasteful number, since it uses less digits than its factorization.

691159649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 542514.

The product of its digits is 524880, while the sum is 50.

The square root of 691159649 is about 26289.9153479048. The cubic root of 691159649 is about 884.1503539737.

The spelling of 691159649 in words is "six hundred ninety-one million, one hundred fifty-nine thousand, six hundred forty-nine".