6921390 has 64 divisors (see below), whose sum is σ = 19823616. Its totient is φ = 1512192.

The previous prime is 6921389. The next prime is 6921403. The reversal of 6921390 is 931296.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4114 + ... + 5546.

It is an arithmetic number, because the mean of its divisors is an integer number (309744).

Almost surely, 2^6921390 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6921390, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9911808).

6921390 is an abundant number, since it is smaller than the sum of its proper divisors (12902226).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6921390 is a wasteful number, since it uses less digits than its factorization.

6921390 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1473.

The product of its (nonzero) digits is 2916, while the sum is 30.

The square root of 6921390 is about 2630.8534736849. The cubic root of 6921390 is about 190.5743470182.

The spelling of 6921390 in words is "six million, nine hundred twenty-one thousand, three hundred ninety".