1659398978 has 8 divisors (see below), whose sum is σ = 2489323980. Its totient is φ = 829624320.

The previous prime is 1659398971. The next prime is 1659398987. The reversal of 1659398978 is 8798939561.

It can be written as a sum of positive squares in 2 ways, for example, as 1631594449 + 27804529 = 40393^2 + 5273^2 .

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

It is not an unprimeable number, because it can be changed into a prime (1659398971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3983 + ... + 57746.

Almost surely, 2^1659398978 is an apocalyptic number.

1659398978 is a deficient number, since it is larger than the sum of its proper divisors (829925002).

1659398978 is a wasteful number, since it uses less digits than its factorization.

1659398978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75172.

The product of its digits is 29393280, while the sum is 65.

The square root of 1659398978 is about 40735.7211547801. The cubic root of 1659398978 is about 1183.9052308986.

The spelling of 1659398978 in words is "one billion, six hundred fifty-nine million, three hundred ninety-eight thousand, nine hundred seventy-eight".