1603981 has 4 divisors (see below), whose sum is σ = 1619964. Its totient is φ = 1588000.

The previous prime is 1603963. The next prime is 1604003. The reversal of 1603981 is 1893061.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1893061 = 23 ⋅82307.

It can be written as a sum of positive squares in 2 ways, for example, as 1522756 + 81225 = 1234^2 + 285^2 .

It is a cyclic number.

It is not a de Polignac number, because 1603981 - 2⁵ = 1603949 is a prime.

It is a super-2 number, since 2×1603981² = 5145510096722, which contains 22 as substring.

It is a Duffinian number.

1603981 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1603081) 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 in 3 ways as a sum of consecutive naturals, for example, 7840 + ... + 8041.

It is an arithmetic number, because the mean of its divisors is an integer number (404991).

2^1603981 is an apocalyptic number.

It is an amenable number.

1603981 is a deficient number, since it is larger than the sum of its proper divisors (15983).

1603981 is a wasteful number, since it uses less digits than its factorization.

1603981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15982.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 1603981 is about 1266.4837148578. The cubic root of 1603981 is about 117.0576334751.

The spelling of 1603981 in words is "one million, six hundred three thousand, nine hundred eighty-one".