39724021 has 2 divisors, whose sum is σ = 39724022. Its totient is φ = 39724020.

The previous prime is 39724001. The next prime is 39724043. The reversal of 39724021 is 12042793.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22667121 + 17056900 = 4761^2 + 4130^2 .

It is a cyclic number.

It is not a de Polignac number, because 39724021 - 2²³ = 31335413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (39724001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19862010 + 19862011.

It is an arithmetic number, because the mean of its divisors is an integer number (19862011).

Almost surely, 2^39724021 is an apocalyptic number.

It is an amenable number.

39724021 is a deficient number, since it is larger than the sum of its proper divisors (1).

39724021 is an equidigital number, since it uses as much as digits as its factorization.

39724021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 39724021 is about 6302.6995010075. The cubic root of 39724021 is about 341.2068444042.

The spelling of 39724021 in words is "thirty-nine million, seven hundred twenty-four thousand, twenty-one".