866721801 has 16 divisors (see below), whose sum is σ = 1263849408. Its totient is φ = 523968000.

The previous prime is 866721799. The next prime is 866721899. The reversal of 866721801 is 108127668.

It is not a de Polignac number, because 866721801 - 2¹ = 866721799 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 866721801.

It is not an unprimeable number, because it can be changed into a prime (866721301) 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, 19516 + ... + 45981.

It is an arithmetic number, because the mean of its divisors is an integer number (78990588).

Almost surely, 2^866721801 is an apocalyptic number.

It is an amenable number.

866721801 is a deficient number, since it is larger than the sum of its proper divisors (397127607).

866721801 is a wasteful number, since it uses less digits than its factorization.

866721801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65912.

The product of its (nonzero) digits is 32256, while the sum is 39.

The square root of 866721801 is about 29440.1392829586. The cubic root of 866721801 is about 953.4397193152.

The spelling of 866721801 in words is "eight hundred sixty-six million, seven hundred twenty-one thousand, eight hundred one".