1978998818 has 4 divisors (see below), whose sum is σ = 2968498230. Its totient is φ = 989499408.

The previous prime is 1978998817. The next prime is 1978998841. The reversal of 1978998818 is 8188998791.

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

It can be written as a sum of positive squares in only one way, i.e., 1662763729 + 316235089 = 40777^2 + 17783^2 .

It is not an unprimeable number, because it can be changed into a prime (1978998817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494749703 + ... + 494749706.

Almost surely, 2^1978998818 is an apocalyptic number.

1978998818 is a deficient number, since it is larger than the sum of its proper divisors (989499412).

1978998818 is an equidigital number, since it uses as much as digits as its factorization.

1978998818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 989499411.

The product of its digits is 20901888, while the sum is 68.

The square root of 1978998818 is about 44485.9395539759. The cubic root of 1978998818 is about 1255.4955515631.

The spelling of 1978998818 in words is "one billion, nine hundred seventy-eight million, nine hundred ninety-eight thousand, eight hundred eighteen".