7821221287 has 4 divisors (see below), whose sum is σ = 8532241416. Its totient is φ = 7110201160.

The previous prime is 7821221273. The next prime is 7821221293.

7821221287 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is not a de Polignac number, because 7821221287 - 2¹¹ = 7821219239 is a prime.

It is a super-2 number, since 2×7821221287² (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 (7821221257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 355510048 + ... + 355510069.

It is an arithmetic number, because the mean of its divisors is an integer number (2133060354).

Almost surely, 2^7821221287 is an apocalyptic number.

7821221287 is a deficient number, since it is larger than the sum of its proper divisors (711020129).

7821221287 is a wasteful number, since it uses less digits than its factorization.

7821221287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 711020128.

The product of its digits is 50176, while the sum is 40.

The square root of 7821221287 is about 88437.6689369411. The cubic root of 7821221287 is about 1984.9893966572.

It can be divided in two parts, 78212 and 21287, that added together give a palindrome (99499).

The spelling of 7821221287 in words is "seven billion, eight hundred twenty-one million, two hundred twenty-one thousand, two hundred eighty-seven".