6921399 has 8 divisors (see below), whose sum is σ = 9262960. Its totient is φ = 4597056.

The previous prime is 6921389. The next prime is 6921403. The reversal of 6921399 is 9931296.

It is a happy number.

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

It is not a de Polignac number, because 6921399 - 2²¹ = 4824247 is a prime.

It is a Duffinian number.

6921399 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6921319) 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, 3334 + ... + 4995.

It is an arithmetic number, because the mean of its divisors is an integer number (1157870).

Almost surely, 2^6921399 is an apocalyptic number.

6921399 is a deficient number, since it is larger than the sum of its proper divisors (2341561).

6921399 is a wasteful number, since it uses less digits than its factorization.

6921399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8609.

The product of its digits is 26244, while the sum is 39.

The square root of 6921399 is about 2630.8551841559. The cubic root of 6921399 is about 190.5744296205.

The spelling of 6921399 in words is "six million, nine hundred twenty-one thousand, three hundred ninety-nine".