247051991 has 2 divisors, whose sum is σ = 247051992. Its totient is φ = 247051990.

The previous prime is 247051967. The next prime is 247051999. The reversal of 247051991 is 199150742.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 247051991 - 2¹⁸ = 246789847 is a prime.

It is a super-2 number, since 2×247051991² = 122069372514128162, which contains 22 as substring.

It is a Sophie Germain prime.

It is equal to p_13526768 and since 247051991 and 13526768 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (247051999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 123525995 + 123525996.

It is an arithmetic number, because the mean of its divisors is an integer number (123525996).

Almost surely, 2^247051991 is an apocalyptic number.

247051991 is a deficient number, since it is larger than the sum of its proper divisors (1).

247051991 is an equidigital number, since it uses as much as digits as its factorization.

247051991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 22680, while the sum is 38.

The square root of 247051991 is about 15717.8876125261. The cubic root of 247051991 is about 627.4745552451.

The spelling of 247051991 in words is "two hundred forty-seven million, fifty-one thousand, nine hundred ninety-one".