70728821 has 2 divisors, whose sum is σ = 70728822. Its totient is φ = 70728820.

The previous prime is 70728803. The next prime is 70728839. The reversal of 70728821 is 12882707.

It is a balanced prime because it is at equal distance from previous prime (70728803) and next prime (70728839).

It can be written as a sum of positive squares in only one way, i.e., 41460721 + 29268100 = 6439^2 + 5410^2 .

It is an emirp because it is prime and its reverse (12882707) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 70728821 - 2¹⁴ = 70712437 is a prime.

It is a super-2 number, since 2×70728821² = 10005132240100082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (70728521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35364410 + 35364411.

It is an arithmetic number, because the mean of its divisors is an integer number (35364411).

Almost surely, 2^70728821 is an apocalyptic number.

It is an amenable number.

70728821 is a deficient number, since it is larger than the sum of its proper divisors (1).

70728821 is an equidigital number, since it uses as much as digits as its factorization.

70728821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12544, while the sum is 35.

The square root of 70728821 is about 8410.0428655269. The cubic root of 70728821 is about 413.5539179136.

The spelling of 70728821 in words is "seventy million, seven hundred twenty-eight thousand, eight hundred twenty-one".