7978421 has 8 divisors (see below), whose sum is σ = 8939424. Its totient is φ = 7056720.

The previous prime is 7978409. The next prime is 7978429. The reversal of 7978421 is 1248797.

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

It is not a de Polignac number, because 7978421 - 2¹⁸ = 7716277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7978429) 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, 9395 + ... + 10208.

It is an arithmetic number, because the mean of its divisors is an integer number (1117428).

Almost surely, 2^7978421 is an apocalyptic number.

It is an amenable number.

7978421 is a deficient number, since it is larger than the sum of its proper divisors (961003).

7978421 is a wasteful number, since it uses less digits than its factorization.

7978421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19651.

The product of its digits is 28224, while the sum is 38.

The square root of 7978421 is about 2824.6098845681. The cubic root of 7978421 is about 199.8200130721.

The spelling of 7978421 in words is "seven million, nine hundred seventy-eight thousand, four hundred twenty-one".