85999721 has 6 divisors (see below), whose sum is σ = 87054570. Its totient is φ = 84946928.

The previous prime is 85999679. The next prime is 85999723. The reversal of 85999721 is 12799958.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 61842496 + 24157225 = 7864^2 + 4915^2 .

It is not a de Polignac number, because 85999721 - 2¹⁰ = 85998697 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 85999721.

It is not an unprimeable number, because it can be changed into a prime (85999723) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 86996 + ... + 87978.

It is an arithmetic number, because the mean of its divisors is an integer number (14509095).

Almost surely, 2^85999721 is an apocalyptic number.

It is an amenable number.

85999721 is a deficient number, since it is larger than the sum of its proper divisors (1054849).

85999721 is an frugal number, since it uses more digits than its factorization.

85999721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2055 (or 1072 counting only the distinct ones).

The product of its digits is 408240, while the sum is 50.

The square root of 85999721 is about 9273.6034528116. The cubic root of 85999721 is about 441.4000189153.

The spelling of 85999721 in words is "eighty-five million, nine hundred ninety-nine thousand, seven hundred twenty-one".