1981404 has 36 divisors (see below), whose sum is σ = 5228496. Its totient is φ = 631488.

The previous prime is 1981403. The next prime is 1981409. The reversal of 1981404 is 4041891.

1981404 = T₁₃₅ + T₁₃₆ + ... + T₂₄₂.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-3 number, since 3×1981404³ = 23336749309771881792, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

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 11 ways as a sum of consecutive naturals, for example, 369 + ... + 2024.

It is an arithmetic number, because the mean of its divisors is an integer number (145236).

2^1981404 is an apocalyptic number.

It is an amenable number.

1981404 is an abundant number, since it is smaller than the sum of its proper divisors (3247092).

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

1981404 is a wasteful number, since it uses less digits than its factorization.

1981404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2426 (or 2421 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 1981404 is about 1407.6235292151. The cubic root of 1981404 is about 125.6003969046.

The spelling of 1981404 in words is "one million, nine hundred eighty-one thousand, four hundred four".