39987209 has 4 divisors (see below), whose sum is σ = 40010880. Its totient is φ = 39963540.

The previous prime is 39987203. The next prime is 39987217. The reversal of 39987209 is 90278993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 39987209 - 2⁸ = 39986953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39987203) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9089 + ... + 12750.

It is an arithmetic number, because the mean of its divisors is an integer number (10002720).

Almost surely, 2^39987209 is an apocalyptic number.

It is an amenable number.

39987209 is a deficient number, since it is larger than the sum of its proper divisors (23671).

39987209 is a wasteful number, since it uses less digits than its factorization.

39987209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23670.

The product of its (nonzero) digits is 244944, while the sum is 47.

The square root of 39987209 is about 6323.5440221445. The cubic root of 39987209 is about 341.9587316118.

The spelling of 39987209 in words is "thirty-nine million, nine hundred eighty-seven thousand, two hundred nine".