7826821 has 4 divisors (see below), whose sum is σ = 7879500. Its totient is φ = 7774144.

The previous prime is 7826809. The next prime is 7826837. The reversal of 7826821 is 1286287.

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 509796 + 7317025 = 714^2 + 2705^2 .

It is a cyclic number.

It is not a de Polignac number, because 7826821 - 2¹⁵ = 7794053 is a prime.

It is a super-2 number, since 2×7826821² = 122518253932082, which 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 (7826801) 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, 26116 + ... + 26413.

It is an arithmetic number, because the mean of its divisors is an integer number (1969875).

Almost surely, 2^7826821 is an apocalyptic number.

It is an amenable number.

7826821 is a deficient number, since it is larger than the sum of its proper divisors (52679).

7826821 is a wasteful number, since it uses less digits than its factorization.

7826821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52678.

The product of its digits is 10752, while the sum is 34.

The square root of 7826821 is about 2797.6456173004. The cubic root of 7826821 is about 198.5463010638.

The spelling of 7826821 in words is "seven million, eight hundred twenty-six thousand, eight hundred twenty-one".