39995721 has 16 divisors (see below), whose sum is σ = 59684800. Its totient is φ = 26469504.

The previous prime is 39995699. The next prime is 39995737. The reversal of 39995721 is 12759993.

It is a happy number.

It is not a de Polignac number, because 39995721 - 2¹⁴ = 39979337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39993721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1576 + ... + 9081.

It is an arithmetic number, because the mean of its divisors is an integer number (3730300).

Almost surely, 2^39995721 is an apocalyptic number.

It is an amenable number.

39995721 is a deficient number, since it is larger than the sum of its proper divisors (19689079).

39995721 is a wasteful number, since it uses less digits than its factorization.

39995721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10805 (or 10799 counting only the distinct ones).

The product of its digits is 153090, while the sum is 45.

The square root of 39995721 is about 6324.2170266366. The cubic root of 39995721 is about 341.9829939220.

The spelling of 39995721 in words is "thirty-nine million, nine hundred ninety-five thousand, seven hundred twenty-one".