861275465821 has 4 divisors (see below), whose sum is σ = 861279943644. Its totient is φ = 861270988000.

The previous prime is 861275465807. The next prime is 861275465837. The reversal of 861275465821 is 128564572168.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 224249602500 + 637025863321 = 473550^2 + 798139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861275465821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861275465851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1936810 + ... + 2339611.

It is an arithmetic number, because the mean of its divisors is an integer number (215319985911).

Almost surely, 2^861275465821 is an apocalyptic number.

It is an amenable number.

861275465821 is a deficient number, since it is larger than the sum of its proper divisors (4477823).

861275465821 is a wasteful number, since it uses less digits than its factorization.

861275465821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4477822.

The product of its digits is 6451200, while the sum is 55.

The spelling of 861275465821 in words is "eight hundred sixty-one billion, two hundred seventy-five million, four hundred sixty-five thousand, eight hundred twenty-one".