71720657 has 2 divisors, whose sum is σ = 71720658. Its totient is φ = 71720656.

The previous prime is 71720641. The next prime is 71720659. The reversal of 71720657 is 75602717.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58354321 + 13366336 = 7639^2 + 3656^2 .

It is a cyclic number.

It is not a de Polignac number, because 71720657 - 2⁴ = 71720641 is a prime.

Together with 71720659, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (71720659) 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, 35860328 + 35860329.

It is an arithmetic number, because the mean of its divisors is an integer number (35860329).

Almost surely, 2^71720657 is an apocalyptic number.

It is an amenable number.

71720657 is a deficient number, since it is larger than the sum of its proper divisors (1).

71720657 is an equidigital number, since it uses as much as digits as its factorization.

71720657 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20580, while the sum is 35.

The square root of 71720657 is about 8468.8049334012. The cubic root of 71720657 is about 415.4780517088.

The spelling of 71720657 in words is "seventy-one million, seven hundred twenty thousand, six hundred fifty-seven".