210240991 has 2 divisors, whose sum is σ = 210240992. Its totient is φ = 210240990.

The previous prime is 210240973. The next prime is 210241019. The reversal of 210240991 is 199042012.

It is a happy number.

It is an a-pointer prime, because the next prime (210241019) can be obtained adding 210240991 to its sum of digits (28).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-210240991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (210240911) 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, 105120495 + 105120496.

It is an arithmetic number, because the mean of its divisors is an integer number (105120496).

Almost surely, 2^210240991 is an apocalyptic number.

210240991 is a deficient number, since it is larger than the sum of its proper divisors (1).

210240991 is an equidigital number, since it uses as much as digits as its factorization.

210240991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 210240991 is about 14499.6893414997. The cubic root of 210240991 is about 594.6194784672.

It can be divided in two parts, 2102409 and 91, that added together give a square (2102500 = 1450²).

The spelling of 210240991 in words is "two hundred ten million, two hundred forty thousand, nine hundred ninety-one".