70821521 has 2 divisors, whose sum is σ = 70821522. Its totient is φ = 70821520.

The previous prime is 70821511. The next prime is 70821539. The reversal of 70821521 is 12512807.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68145025 + 2676496 = 8255^2 + 1636^2 .

It is an emirp because it is prime and its reverse (12512807) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 70821521 - 2²² = 66627217 is a prime.

It is not a weakly prime, because it can be changed into another prime (70821511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35410760 + 35410761.

It is an arithmetic number, because the mean of its divisors is an integer number (35410761).

Almost surely, 2^70821521 is an apocalyptic number.

It is an amenable number.

70821521 is a deficient number, since it is larger than the sum of its proper divisors (1).

70821521 is an equidigital number, since it uses as much as digits as its factorization.

70821521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 70821521 is about 8415.5523288730. The cubic root of 70821521 is about 413.7345124313.

The spelling of 70821521 in words is "seventy million, eight hundred twenty-one thousand, five hundred twenty-one".