7827821 has 4 divisors (see below), whose sum is σ = 7938144. Its totient is φ = 7717500.

The previous prime is 7827793. The next prime is 7827823. The reversal of 7827821 is 1287287.

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.

It is a cyclic number.

It is not a de Polignac number, because 7827821 - 2¹⁴ = 7811437 is a prime.

It is a super-4 number, since 4×7827821⁴ (a number of 29 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7827823) 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, 55055 + ... + 55196.

It is an arithmetic number, because the mean of its divisors is an integer number (1984536).

Almost surely, 2^7827821 is an apocalyptic number.

7827821 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

7827821 is the 1496-th centered heptagonal number.

It is an amenable number.

7827821 is a deficient number, since it is larger than the sum of its proper divisors (110323).

7827821 is a wasteful number, since it uses less digits than its factorization.

7827821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110322.

The product of its digits is 12544, while the sum is 35.

The square root of 7827821 is about 2797.8243332990. The cubic root of 7827821 is about 198.5547565123.

The spelling of 7827821 in words is "seven million, eight hundred twenty-seven thousand, eight hundred twenty-one".