7821861 has 8 divisors (see below), whose sum is σ = 10461984. Its totient is φ = 5198160.

The previous prime is 7821859. The next prime is 7821893. The reversal of 7821861 is 1681287.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 7821861 - 2¹ = 7821859 is a prime.

It is a super-4 number, since 4×7821861⁴ (a number of 29 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7821811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2946 + ... + 4931.

It is an arithmetic number, because the mean of its divisors is an integer number (1307748).

Almost surely, 2^7821861 is an apocalyptic number.

It is an amenable number.

7821861 is a deficient number, since it is larger than the sum of its proper divisors (2640123).

7821861 is a wasteful number, since it uses less digits than its factorization.

7821861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8211.

The product of its digits is 5376, while the sum is 33.

The square root of 7821861 is about 2796.7590171482. The cubic root of 7821861 is about 198.5043513905.

The spelling of 7821861 in words is "seven million, eight hundred twenty-one thousand, eight hundred sixty-one".