1981205 has 8 divisors (see below), whose sum is σ = 2401152. Its totient is φ = 1569168.

The previous prime is 1981201. The next prime is 1981237. The reversal of 1981205 is 5021891.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1981205 - 2² = 1981201 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981201) 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, 1409 + ... + 2438.

It is an arithmetic number, because the mean of its divisors is an integer number (300144).

2^1981205 is an apocalyptic number.

It is an amenable number.

1981205 is a deficient number, since it is larger than the sum of its proper divisors (419947).

1981205 is a wasteful number, since it uses less digits than its factorization.

1981205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3955.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 1981205 is about 1407.5528409264. The cubic root of 1981205 is about 125.5961919207.

The spelling of 1981205 in words is "one million, nine hundred eighty-one thousand, two hundred five".