1981406 has 8 divisors (see below), whose sum is σ = 3396720. Its totient is φ = 849168.

The previous prime is 1981403. The next prime is 1981409. The reversal of 1981406 is 6041891.

It is an interprime number because it is at equal distance from previous prime (1981403) and next prime (1981409).

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

It is a super-3 number, since 3×1981406³ = 23336819977155814248, which contains 333 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981403) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70751 + ... + 70778.

It is an arithmetic number, because the mean of its divisors is an integer number (424590).

2^1981406 is an apocalyptic number.

1981406 is a deficient number, since it is larger than the sum of its proper divisors (1415314).

1981406 is a wasteful number, since it uses less digits than its factorization.

1981406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141538.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 1981406 is about 1407.6242396322. The cubic root of 1981406 is about 125.6004391644.

The spelling of 1981406 in words is "one million, nine hundred eighty-one thousand, four hundred six".