39720509 has 4 divisors (see below), whose sum is σ = 39742560. Its totient is φ = 39698460.

The previous prime is 39720503. The next prime is 39720523. The reversal of 39720509 is 90502793.

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 39720509 - 2²⁰ = 38671933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39720503) 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, 8057 + ... + 12014.

It is an arithmetic number, because the mean of its divisors is an integer number (9935640).

Almost surely, 2^39720509 is an apocalyptic number.

It is an amenable number.

39720509 is a deficient number, since it is larger than the sum of its proper divisors (22051).

39720509 is a wasteful number, since it uses less digits than its factorization.

39720509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22050.

The product of its (nonzero) digits is 17010, while the sum is 35.

The square root of 39720509 is about 6302.4208840730. The cubic root of 39720509 is about 341.1967887442.

The spelling of 39720509 in words is "thirty-nine million, seven hundred twenty thousand, five hundred nine".