1981381 has 8 divisors (see below), whose sum is σ = 2081664. Its totient is φ = 1882320.

The previous prime is 1981361. The next prime is 1981393. The reversal of 1981381 is 1831891.

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

It is not a de Polignac number, because 1981381 - 2⁵ = 1981349 is a prime.

It is a super-3 number, since 3×1981381³ = 23335936645110388023, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981361) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6216 + ... + 6526.

It is an arithmetic number, because the mean of its divisors is an integer number (260208).

2^1981381 is an apocalyptic number.

It is an amenable number.

1981381 is a deficient number, since it is larger than the sum of its proper divisors (100283).

1981381 is a wasteful number, since it uses less digits than its factorization.

1981381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611.

The product of its digits is 1728, while the sum is 31.

The square root of 1981381 is about 1407.6153593933. The cubic root of 1981381 is about 125.5999109159.

The spelling of 1981381 in words is "one million, nine hundred eighty-one thousand, three hundred eighty-one".