71197991 has 2 divisors, whose sum is σ = 71197992. Its totient is φ = 71197990.

The previous prime is 71197963. The next prime is 71198033. The reversal of 71197991 is 19979117.

It is a weak prime.

It is an emirp because it is prime and its reverse (19979117) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71197991 - 2¹⁸ = 70935847 is a prime.

It is a Sophie Germain 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 (71197591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35598995 + 35598996.

It is an arithmetic number, because the mean of its divisors is an integer number (35598996).

Almost surely, 2^71197991 is an apocalyptic number.

71197991 is a deficient number, since it is larger than the sum of its proper divisors (1).

71197991 is an equidigital number, since it uses as much as digits as its factorization.

71197991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35721, while the sum is 44.

The square root of 71197991 is about 8437.8901983849. The cubic root of 71197991 is about 414.4663213043.

The spelling of 71197991 in words is "seventy-one million, one hundred ninety-seven thousand, nine hundred ninety-one".