385009991 has 2 divisors, whose sum is σ = 385009992. Its totient is φ = 385009990.

The previous prime is 385009873. The next prime is 385010009. The reversal of 385009991 is 199900583.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-385009991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (385009091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 192504995 + 192504996.

It is an arithmetic number, because the mean of its divisors is an integer number (192504996).

Almost surely, 2^385009991 is an apocalyptic number.

385009991 is a deficient number, since it is larger than the sum of its proper divisors (1).

385009991 is an equidigital number, since it uses as much as digits as its factorization.

385009991 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 385009991 is about 19621.6714629514. The cubic root of 385009991 is about 727.4849276724.

The spelling of 385009991 in words is "three hundred eighty-five million, nine thousand, nine hundred ninety-one".