1991402986 has 16 divisors (see below), whose sum is σ = 3091765248. Its totient is φ = 960987600.

The previous prime is 1991402983. The next prime is 1991402993. The reversal of 1991402986 is 6892041991.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (1991402983) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19930 + ... + 66181.

It is an arithmetic number, because the mean of its divisors is an integer number (193235328).

Almost surely, 2^1991402986 is an apocalyptic number.

1991402986 is a deficient number, since it is larger than the sum of its proper divisors (1100362262).

1991402986 is a wasteful number, since it uses less digits than its factorization.

1991402986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86517.

The product of its (nonzero) digits is 279936, while the sum is 49.

The square root of 1991402986 is about 44625.1384983845. The cubic root of 1991402986 is about 1258.1131972419.

The spelling of 1991402986 in words is "one billion, nine hundred ninety-one million, four hundred two thousand, nine hundred eighty-six".