381399981 has 16 divisors (see below), whose sum is σ = 550972224. Its totient is φ = 233743104.

The previous prime is 381399911. The next prime is 381399983. The reversal of 381399981 is 189993183.

It is a happy number.

It is not a de Polignac number, because 381399981 - 2⁷ = 381399853 is a prime.

It is a super-2 number, since 2×381399981² = 290931891013600722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (381399983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84766 + ... + 89151.

It is an arithmetic number, because the mean of its divisors is an integer number (34435764).

Almost surely, 2^381399981 is an apocalyptic number.

It is an amenable number.

381399981 is a deficient number, since it is larger than the sum of its proper divisors (169572243).

381399981 is a wasteful number, since it uses less digits than its factorization.

381399981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 173980.

The product of its digits is 419904, while the sum is 51.

The square root of 381399981 is about 19529.4644319807. The cubic root of 381399981 is about 725.2040525914.

The spelling of 381399981 in words is "three hundred eighty-one million, three hundred ninety-nine thousand, nine hundred eighty-one".