39930721 has 2 divisors, whose sum is σ = 39930722. Its totient is φ = 39930720.

The previous prime is 39930689. The next prime is 39930749. The reversal of 39930721 is 12703993.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31584400 + 8346321 = 5620^2 + 2889^2 .

It is a cyclic number.

It is not a de Polignac number, because 39930721 - 2⁵ = 39930689 is a prime.

It is not a weakly prime, because it can be changed into another prime (39930421) 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 as a sum of consecutive naturals, namely, 19965360 + 19965361.

It is an arithmetic number, because the mean of its divisors is an integer number (19965361).

Almost surely, 2^39930721 is an apocalyptic number.

It is an amenable number.

39930721 is a deficient number, since it is larger than the sum of its proper divisors (1).

39930721 is an equidigital number, since it uses as much as digits as its factorization.

39930721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10206, while the sum is 34.

The square root of 39930721 is about 6319.0759609297. The cubic root of 39930721 is about 341.7976328644.

The spelling of 39930721 in words is "thirty-nine million, nine hundred thirty thousand, seven hundred twenty-one".