39947521 has 2 divisors, whose sum is σ = 39947522. Its totient is φ = 39947520.

The previous prime is 39947491. The next prime is 39947563. The reversal of 39947521 is 12574993.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37271025 + 2676496 = 6105^2 + 1636^2 .

It is an emirp because it is prime and its reverse (12574993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 39947521 - 2⁷ = 39947393 is a prime.

It is not a weakly prime, because it can be changed into another prime (39947581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19973760 + 19973761.

It is an arithmetic number, because the mean of its divisors is an integer number (19973761).

Almost surely, 2^39947521 is an apocalyptic number.

It is an amenable number.

39947521 is a deficient number, since it is larger than the sum of its proper divisors (1).

39947521 is an equidigital number, since it uses as much as digits as its factorization.

39947521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 68040, while the sum is 40.

The square root of 39947521 is about 6320.4051294201. The cubic root of 39947521 is about 341.8455608338.

The spelling of 39947521 in words is "thirty-nine million, nine hundred forty-seven thousand, five hundred twenty-one".