387909981 has 6 divisors (see below), whose sum is σ = 560314430. Its totient is φ = 258606648.

The previous prime is 387909959. The next prime is 387909983. The reversal of 387909981 is 189909783.

It can be written as a sum of positive squares in only one way, i.e., 238239225 + 149670756 = 15435^2 + 12234^2 .

It is not a de Polignac number, because 387909981 - 2⁷ = 387909853 is a prime.

It is a super-2 number, since 2×387909981² = 300948306718840722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (387909983) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 21550546 + ... + 21550563.

Almost surely, 2^387909981 is an apocalyptic number.

It is an amenable number.

387909981 is a deficient number, since it is larger than the sum of its proper divisors (172404449).

387909981 is a wasteful number, since it uses less digits than its factorization.

387909981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43101115 (or 43101112 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The square root of 387909981 is about 19695.4304598808. The cubic root of 387909981 is about 729.3068926389.

The spelling of 387909981 in words is "three hundred eighty-seven million, nine hundred nine thousand, nine hundred eighty-one".