209145931 has 2 divisors, whose sum is σ = 209145932. Its totient is φ = 209145930.

The previous prime is 209145919. The next prime is 209145947. The reversal of 209145931 is 139541902.

209145931 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 is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-209145931 is a prime.

It is a super-2 number, since 2×209145931² = 87484040907713522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209145971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104572965 + 104572966.

It is an arithmetic number, because the mean of its divisors is an integer number (104572966).

Almost surely, 2^209145931 is an apocalyptic number.

209145931 is a deficient number, since it is larger than the sum of its proper divisors (1).

209145931 is an equidigital number, since it uses as much as digits as its factorization.

209145931 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 209145931 is about 14461.8785432599. The cubic root of 209145931 is about 593.5853036683.

The spelling of 209145931 in words is "two hundred nine million, one hundred forty-five thousand, nine hundred thirty-one".