2158978618 has 4 divisors (see below), whose sum is σ = 3238467930. Its totient is φ = 1079489308.

The previous prime is 2158978609. The next prime is 2158978637. The reversal of 2158978618 is 8168798512.

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., 2126408769 + 32569849 = 46113^2 + 5707^2 .

It is a super-2 number, since 2×2158978618² = 9322377345962379848, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 539744653 + ... + 539744656.

Almost surely, 2^2158978618 is an apocalyptic number.

2158978618 is a deficient number, since it is larger than the sum of its proper divisors (1079489312).

2158978618 is a wasteful number, since it uses less digits than its factorization.

2158978618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1079489311.

The product of its digits is 1935360, while the sum is 55.

The square root of 2158978618 is about 46464.8105344249. The cubic root of 2158978618 is about 1292.4570318202.

The spelling of 2158978618 in words is "two billion, one hundred fifty-eight million, nine hundred seventy-eight thousand, six hundred eighteen".