70809721 has 2 divisors, whose sum is σ = 70809722. Its totient is φ = 70809720.

The previous prime is 70809703. The next prime is 70809733. The reversal of 70809721 is 12790807.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 60279696 + 10530025 = 7764^2 + 3245^2 .

It is an emirp because it is prime and its reverse (12790807) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 70809721 - 2⁵ = 70809689 is a prime.

It is not a weakly prime, because it can be changed into another prime (70806721) 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, 35404860 + 35404861.

It is an arithmetic number, because the mean of its divisors is an integer number (35404861).

Almost surely, 2^70809721 is an apocalyptic number.

It is an amenable number.

70809721 is a deficient number, since it is larger than the sum of its proper divisors (1).

70809721 is an equidigital number, since it uses as much as digits as its factorization.

70809721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 34.

The square root of 70809721 is about 8414.8512167477. The cubic root of 70809721 is about 413.7115328890.

The spelling of 70809721 in words is "seventy million, eight hundred nine thousand, seven hundred twenty-one".