8420391 has 12 divisors (see below), whose sum is σ = 13900432. Its totient is φ = 4811616.

The previous prime is 8420351. The next prime is 8420393. The reversal of 8420391 is 1930248.

It is not a de Polignac number, because 8420391 - 2⁶ = 8420327 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8420393) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 66766 + ... + 66891.

Almost surely, 2^8420391 is an apocalyptic number.

8420391 is a deficient number, since it is larger than the sum of its proper divisors (5480041).

8420391 is a wasteful number, since it uses less digits than its factorization.

8420391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133670 (or 133667 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 8420391 is about 2901.7909986765. The cubic root of 8420391 is about 203.4436252553.

The spelling of 8420391 in words is "eight million, four hundred twenty thousand, three hundred ninety-one".