1981699 has 2 divisors, whose sum is σ = 1981700. Its totient is φ = 1981698.

The previous prime is 1981691. The next prime is 1981711. The reversal of 1981699 is 9961891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1981699 - 2³ = 1981691 is a prime.

It is not a weakly prime, because it can be changed into another prime (1981691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990849 + 990850.

It is an arithmetic number, because the mean of its divisors is an integer number (990850).

2^1981699 is an apocalyptic number.

1981699 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981699 is an equidigital number, since it uses as much as digits as its factorization.

1981699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34992, while the sum is 43.

The square root of 1981699 is about 1407.7283118557. The cubic root of 1981699 is about 125.6066299055.

It can be divided in two parts, 19 and 81699, that added together give a palindrome (81718).

The spelling of 1981699 in words is "one million, nine hundred eighty-one thousand, six hundred ninety-nine".