387171981 has 30 divisors (see below), whose sum is σ = 672802350. Its totient is φ = 221238864.

The previous prime is 387171977. The next prime is 387172007. The reversal of 387171981 is 189171783.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 289340100 + 97831881 = 17010^2 + 9891^2 .

It is not a de Polignac number, because 387171981 - 2² = 387171977 is a prime.

It is a super-2 number, since 2×387171981² = 299804285742928722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (387171901) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 44806 + ... + 52743.

It is an arithmetic number, because the mean of its divisors is an integer number (22426745).

Almost surely, 2^387171981 is an apocalyptic number.

It is an amenable number.

387171981 is a deficient number, since it is larger than the sum of its proper divisors (285630369).

387171981 is an equidigital number, since it uses as much as digits as its factorization.

387171981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97575 (or 97559 counting only the distinct ones).

The product of its digits is 84672, while the sum is 45.

The square root of 387171981 is about 19676.6862301557. The cubic root of 387171981 is about 728.8440961126.

The spelling of 387171981 in words is "three hundred eighty-seven million, one hundred seventy-one thousand, nine hundred eighty-one".