7840021 has 8 divisors (see below), whose sum is σ = 9011520. Its totient is φ = 6681408.

The previous prime is 7840013. The next prime is 7840031. The reversal of 7840021 is 1200487.

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

It is a cyclic number.

It is not a de Polignac number, because 7840021 - 2³ = 7840013 is a prime.

It is a super-2 number, since 2×7840021² = 122931858560882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 7839974 and 7840001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7840031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1876 + ... + 4381.

It is an arithmetic number, because the mean of its divisors is an integer number (1126440).

Almost surely, 2^7840021 is an apocalyptic number.

It is an amenable number.

7840021 is a deficient number, since it is larger than the sum of its proper divisors (1171499).

7840021 is a wasteful number, since it uses less digits than its factorization.

7840021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6443.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 7840021 is about 2800.0037499975. The cubic root of 7840021 is about 198.6578550486.

The spelling of 7840021 in words is "seven million, eight hundred forty thousand, twenty-one".