1978659505 has 4 divisors (see below), whose sum is σ = 2374391412. Its totient is φ = 1582927600.

The previous prime is 1978659503. The next prime is 1978659511. The reversal of 1978659505 is 5059568791.

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 249513616 + 1729145889 = 15796^2 + 41583^2 .

It is not a de Polignac number, because 1978659505 - 2¹ = 1978659503 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978659503) 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, 197865946 + ... + 197865955.

It is an arithmetic number, because the mean of its divisors is an integer number (593597853).

Almost surely, 2^1978659505 is an apocalyptic number.

It is an amenable number.

1978659505 is a deficient number, since it is larger than the sum of its proper divisors (395731907).

1978659505 is an equidigital number, since it uses as much as digits as its factorization.

1978659505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395731906.

The product of its (nonzero) digits is 3402000, while the sum is 55.

The square root of 1978659505 is about 44482.1256798728. The cubic root of 1978659505 is about 1255.4237930039.

The spelling of 1978659505 in words is "one billion, nine hundred seventy-eight million, six hundred fifty-nine thousand, five hundred five".