1981599 has 8 divisors (see below), whose sum is σ = 2733360. Its totient is φ = 1275456.

The previous prime is 1981597. The next prime is 1981607. The reversal of 1981599 is 9951891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1981599 - 2¹ = 1981597 is a prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 1981599.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981597) 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, 11302 + ... + 11475.

It is an arithmetic number, because the mean of its divisors is an integer number (341670).

2^1981599 is an apocalyptic number.

1981599 is a deficient number, since it is larger than the sum of its proper divisors (751761).

1981599 is a wasteful number, since it uses less digits than its factorization.

1981599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22809.

The product of its digits is 29160, while the sum is 42.

The square root of 1981599 is about 1407.6927931903. The cubic root of 1981599 is about 125.6045170931.

It can be divided in two parts, 19 and 81599, that added together give a palindrome (81618).

The spelling of 1981599 in words is "one million, nine hundred eighty-one thousand, five hundred ninety-nine".