39890721 has 16 divisors (see below), whose sum is σ = 60649344. Its totient is φ = 23103744.

The previous prime is 39890693. The next prime is 39890737. The reversal of 39890721 is 12709893.

It is not a de Polignac number, because 39890721 - 2¹⁰ = 39889697 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a self number, because there is not a number n which added to its sum of digits gives 39890721.

It is not an unprimeable number, because it can be changed into a prime (39890021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29421 + ... + 30746.

It is an arithmetic number, because the mean of its divisors is an integer number (3790584).

Almost surely, 2^39890721 is an apocalyptic number.

It is an amenable number.

39890721 is a deficient number, since it is larger than the sum of its proper divisors (20758623).

39890721 is a wasteful number, since it uses less digits than its factorization.

39890721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60200.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 39890721 is about 6315.9101481893. The cubic root of 39890721 is about 341.6834645188.

It can be divided in two parts, 398 and 90721, that added together give a palindrome (91119).

The spelling of 39890721 in words is "thirty-nine million, eight hundred ninety thousand, seven hundred twenty-one".