1286861986 has 4 divisors (see below), whose sum is σ = 1930292982. Its totient is φ = 643430992.

The previous prime is 1286861981. The next prime is 1286862019. The reversal of 1286861986 is 6891686821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6891686821 = 19 ⋅362720359.

It can be written as a sum of positive squares in only one way, i.e., 1283000761 + 3861225 = 35819^2 + 1965^2 .

It is not an unprimeable number, because it can be changed into a prime (1286861981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321715495 + ... + 321715498.

Almost surely, 2^1286861986 is an apocalyptic number.

1286861986 is a deficient number, since it is larger than the sum of its proper divisors (643430996).

1286861986 is an equidigital number, since it uses as much as digits as its factorization.

1286861986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643430995.

The product of its digits is 1990656, while the sum is 55.

The square root of 1286861986 is about 35872.8586259863. The cubic root of 1286861986 is about 1087.7038289013.

The spelling of 1286861986 in words is "one billion, two hundred eighty-six million, eight hundred sixty-one thousand, nine hundred eighty-six".