70991 has 2 divisors, whose sum is σ = 70992. Its totient is φ = 70990.

The previous prime is 70981. The next prime is 70997. The reversal of 70991 is 19907.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-70991 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 70991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (70997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35495 + 35496.

It is an arithmetic number, because the mean of its divisors is an integer number (35496).

2⁷⁰⁹⁹¹ is an apocalyptic number.

70991 is a deficient number, since it is larger than the sum of its proper divisors (1).

70991 is an equidigital number, since it uses as much as digits as its factorization.

70991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 567, while the sum is 26.

The square root of 70991 is about 266.4413631552. The cubic root of 70991 is about 41.4064277790.

Adding to 70991 its sum of digits (26), we get a palindrome (71017).

The spelling of 70991 in words is "seventy thousand, nine hundred ninety-one".