39721613 has 4 divisors (see below), whose sum is σ = 40007520. Its totient is φ = 39435708.

The previous prime is 39721603. The next prime is 39721631. The reversal of 39721613 is 31612793.

It is a happy number.

39721613 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31612793 = 2447 ⋅12919.

It is a cyclic number.

It is not a de Polignac number, because 39721613 - 2¹⁰ = 39720589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 39721613.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39721603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 142745 + ... + 143022.

It is an arithmetic number, because the mean of its divisors is an integer number (10001880).

Almost surely, 2^39721613 is an apocalyptic number.

It is an amenable number.

39721613 is a deficient number, since it is larger than the sum of its proper divisors (285907).

39721613 is a wasteful number, since it uses less digits than its factorization.

39721613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285906.

The product of its digits is 6804, while the sum is 32.

The square root of 39721613 is about 6302.5084688559. The cubic root of 39721613 is about 341.1999498128.

The spelling of 39721613 in words is "thirty-nine million, seven hundred twenty-one thousand, six hundred thirteen".