856641001 has 4 divisors (see below), whose sum is σ = 871160400. Its totient is φ = 842121604.

The previous prime is 856640989. The next prime is 856641013. The reversal of 856641001 is 100146658.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 100146658 = 2 ⋅50073329.

It is an interprime number because it is at equal distance from previous prime (856640989) and next prime (856641013).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-856641001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (856641041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7259611 + ... + 7259728.

It is an arithmetic number, because the mean of its divisors is an integer number (217790100).

Almost surely, 2^856641001 is an apocalyptic number.

It is an amenable number.

856641001 is a deficient number, since it is larger than the sum of its proper divisors (14519399).

856641001 is a wasteful number, since it uses less digits than its factorization.

856641001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14519398.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 856641001 is about 29268.4301082241. The cubic root of 856641001 is about 949.7288241704.

Adding to 856641001 its reverse (100146658), we get a palindrome (956787659).

The spelling of 856641001 in words is "eight hundred fifty-six million, six hundred forty-one thousand, one".