39940921 has 2 divisors, whose sum is σ = 39940922. Its totient is φ = 39940920.

The previous prime is 39940919. The next prime is 39940931. The reversal of 39940921 is 12904993.

39940921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37994896 + 1946025 = 6164^2 + 1395^2 .

It is an emirp because it is prime and its reverse (12904993) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 39940921 - 2¹ = 39940919 is a prime.

Together with 39940919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (39940931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19970460 + 19970461.

It is an arithmetic number, because the mean of its divisors is an integer number (19970461).

Almost surely, 2^39940921 is an apocalyptic number.

It is an amenable number.

39940921 is a deficient number, since it is larger than the sum of its proper divisors (1).

39940921 is an equidigital number, since it uses as much as digits as its factorization.

39940921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 39940921 is about 6319.8829894231. The cubic root of 39940921 is about 341.8267335915.

The spelling of 39940921 in words is "thirty-nine million, nine hundred forty thousand, nine hundred twenty-one".