39745721 has 2 divisors, whose sum is σ = 39745722. Its totient is φ = 39745720.

The previous prime is 39745703. The next prime is 39745781. The reversal of 39745721 is 12754793.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34386496 + 5359225 = 5864^2 + 2315^2 .

It is an emirp because it is prime and its reverse (12754793) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39745721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (39745781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19872860 + 19872861.

It is an arithmetic number, because the mean of its divisors is an integer number (19872861).

Almost surely, 2^39745721 is an apocalyptic number.

It is an amenable number.

39745721 is a deficient number, since it is larger than the sum of its proper divisors (1).

39745721 is an equidigital number, since it uses as much as digits as its factorization.

39745721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52920, while the sum is 38.

The square root of 39745721 is about 6304.4207505527. The cubic root of 39745721 is about 341.2689633314.

The spelling of 39745721 in words is "thirty-nine million, seven hundred forty-five thousand, seven hundred twenty-one".