387209681 has 2 divisors, whose sum is σ = 387209682. Its totient is φ = 387209680.

The previous prime is 387209677. The next prime is 387209729. The reversal of 387209681 is 186902783.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 252301456 + 134908225 = 15884^2 + 11615^2 .

It is an emirp because it is prime and its reverse (186902783) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 387209681 - 2² = 387209677 is a prime.

It is a super-2 number, since 2×387209681² = 299862674120243522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (387209611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 193604840 + 193604841.

It is an arithmetic number, because the mean of its divisors is an integer number (193604841).

Almost surely, 2^387209681 is an apocalyptic number.

It is an amenable number.

387209681 is a deficient number, since it is larger than the sum of its proper divisors (1).

387209681 is an equidigital number, since it uses as much as digits as its factorization.

387209681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 44.

The square root of 387209681 is about 19677.6441933479. The cubic root of 387209681 is about 728.8677518625.

The spelling of 387209681 in words is "three hundred eighty-seven million, two hundred nine thousand, six hundred eighty-one".