1678536661 has 8 divisors (see below), whose sum is σ = 1684719000. Its totient is φ = 1672366080.

The previous prime is 1678536649. The next prime is 1678536721. The reversal of 1678536661 is 1666358761.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 535691025 + 1142845636 = 23145^2 + 33806^2 .

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 1678536661 - 2⁹ = 1678536149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1678536641) 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, 360931 + ... + 365551.

It is an arithmetic number, because the mean of its divisors is an integer number (210589875).

Almost surely, 2^1678536661 is an apocalyptic number.

It is an amenable number.

1678536661 is a deficient number, since it is larger than the sum of its proper divisors (6182339).

1678536661 is an equidigital number, since it uses as much as digits as its factorization.

1678536661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5879.

The product of its digits is 1088640, while the sum is 49.

The square root of 1678536661 is about 40969.9482669920. The cubic root of 1678536661 is about 1188.4391326382.

The spelling of 1678536661 in words is "one billion, six hundred seventy-eight million, five hundred thirty-six thousand, six hundred sixty-one".