1986666890 has 32 divisors (see below), whose sum is σ = 3945016656. Its totient is φ = 715645440.

The previous prime is 1986666839. The next prime is 1986666901. The reversal of 1986666890 is 986666891.

It can be written as a sum of positive squares in 8 ways, for example, as 340660849 + 1646006041 = 18457^2 + 40571^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 181037 + ... + 191696.

Almost surely, 2^1986666890 is an apocalyptic number.

1986666890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1986666890 is a deficient number, since it is larger than the sum of its proper divisors (1958349766).

1986666890 is a wasteful number, since it uses less digits than its factorization.

1986666890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 372794.

The product of its (nonzero) digits is 6718464, while the sum is 59.

The square root of 1986666890 is about 44572.0415731656. The cubic root of 1986666890 is about 1257.1150274671.

Subtracting from 1986666890 its reverse (986666891), we obtain a palindrome (999999999).

The spelling of 1986666890 in words is "one billion, nine hundred eighty-six million, six hundred sixty-six thousand, eight hundred ninety".