90870721 has 2 divisors, whose sum is σ = 90870722. Its totient is φ = 90870720.

The previous prime is 90870709. The next prime is 90870751. The reversal of 90870721 is 12707809.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 87684496 + 3186225 = 9364^2 + 1785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-90870721 is a prime.

It is not a weakly prime, because it can be changed into another prime (90870701) 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, 45435360 + 45435361.

It is an arithmetic number, because the mean of its divisors is an integer number (45435361).

Almost surely, 2^90870721 is an apocalyptic number.

It is an amenable number.

90870721 is a deficient number, since it is larger than the sum of its proper divisors (1).

90870721 is an equidigital number, since it uses as much as digits as its factorization.

90870721 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 90870721 is about 9532.6135450883. The cubic root of 90870721 is about 449.5810438119.

The spelling of 90870721 in words is "ninety million, eight hundred seventy thousand, seven hundred twenty-one".