85218721 has 16 divisors (see below), whose sum is σ = 100864000. Its totient is φ = 70457040.

The previous prime is 85218709. The next prime is 85218737. The reversal of 85218721 is 12781258.

It is a cyclic number.

It is not a de Polignac number, because 85218721 - 2¹¹ = 85216673 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (85218701) 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 in 15 ways as a sum of consecutive naturals, for example, 107890 + ... + 108676.

It is an arithmetic number, because the mean of its divisors is an integer number (6304000).

Almost surely, 2^85218721 is an apocalyptic number.

It is an amenable number.

85218721 is a deficient number, since it is larger than the sum of its proper divisors (15645279).

85218721 is a wasteful number, since it uses less digits than its factorization.

85218721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1324.

The product of its digits is 8960, while the sum is 34.

The square root of 85218721 is about 9231.3986480923. The cubic root of 85218721 is about 440.0597732156.

Adding to 85218721 its reverse (12781258), we get a palindrome (97999979).

The spelling of 85218721 in words is "eighty-five million, two hundred eighteen thousand, seven hundred twenty-one".