1981806 has 16 divisors (see below), whose sum is σ = 3977424. Its totient is φ = 658304.

The previous prime is 1981787. The next prime is 1981813. The reversal of 1981806 is 6081891.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3046 + ... + 3638.

It is an arithmetic number, because the mean of its divisors is an integer number (248589).

2^1981806 is an apocalyptic number.

1981806 is an abundant number, since it is smaller than the sum of its proper divisors (1995618).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1981806 is a wasteful number, since it uses less digits than its factorization.

1981806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1155.

The product of its (nonzero) digits is 3456, while the sum is 33.

The square root of 1981806 is about 1407.7663158351. The cubic root of 1981806 is about 125.6088905360.

The spelling of 1981806 in words is "one million, nine hundred eighty-one thousand, eight hundred six".