7821381 has 8 divisors (see below), whose sum is σ = 10446624. Its totient is φ = 5205200.

The previous prime is 7821371. The next prime is 7821383. The reversal of 7821381 is 1831287.

It is a happy number.

7821381 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7821381 is a prime.

It is a super-2 number, since 2×7821381² = 122348001494322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7821383) 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, 106 + ... + 3956.

It is an arithmetic number, because the mean of its divisors is an integer number (1305828).

Almost surely, 2^7821381 is an apocalyptic number.

It is an amenable number.

7821381 is a deficient number, since it is larger than the sum of its proper divisors (2625243).

7821381 is a wasteful number, since it uses less digits than its factorization.

7821381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4531.

The product of its digits is 2688, while the sum is 30.

The square root of 7821381 is about 2796.6732022172. The cubic root of 7821381 is about 198.5002908036.

The spelling of 7821381 in words is "seven million, eight hundred twenty-one thousand, three hundred eighty-one".