39905891 has 2 divisors, whose sum is σ = 39905892. Its totient is φ = 39905890.

The previous prime is 39905861. The next prime is 39905903. The reversal of 39905891 is 19850993.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-39905891 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (39905861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19952945 + 19952946.

It is an arithmetic number, because the mean of its divisors is an integer number (19952946).

Almost surely, 2^39905891 is an apocalyptic number.

39905891 is a deficient number, since it is larger than the sum of its proper divisors (1).

39905891 is an equidigital number, since it uses as much as digits as its factorization.

39905891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 87480, while the sum is 44.

The square root of 39905891 is about 6317.1109694227. The cubic root of 39905891 is about 341.7267718437.

The spelling of 39905891 in words is "thirty-nine million, nine hundred five thousand, eight hundred ninety-one".