7821221807 has 16 divisors (see below), whose sum is σ = 9962461440. Its totient is φ = 5977473408.

The previous prime is 7821221791. The next prime is 7821221813. The reversal of 7821221807 is 7081221287.

It is a cyclic number.

It is not a de Polignac number, because 7821221807 - 2⁴ = 7821221791 is a prime.

It is a super-2 number, since 2×7821221807² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7821221867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1727333 + ... + 1731854.

It is an arithmetic number, because the mean of its divisors is an integer number (622653840).

Almost surely, 2^7821221807 is an apocalyptic number.

7821221807 is a deficient number, since it is larger than the sum of its proper divisors (2141239633).

7821221807 is a wasteful number, since it uses less digits than its factorization.

7821221807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3459230.

The product of its (nonzero) digits is 25088, while the sum is 38.

The square root of 7821221807 is about 88437.6718768648. The cubic root of 7821221807 is about 1984.9894406484.

The spelling of 7821221807 in words is "seven billion, eight hundred twenty-one million, two hundred twenty-one thousand, eight hundred seven".