8400391 has 4 divisors (see below), whose sum is σ = 8446984. Its totient is φ = 8353800.

The previous prime is 8400377. The next prime is 8400409. The reversal of 8400391 is 1930048.

8400391 = 119² + 120² + ... + 299².

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 8400391 - 2¹¹ = 8398343 is a prime.

It is a Duffinian number.

8400391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8400311) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23025 + ... + 23386.

It is an arithmetic number, because the mean of its divisors is an integer number (2111746).

Almost surely, 2^8400391 is an apocalyptic number.

8400391 is a deficient number, since it is larger than the sum of its proper divisors (46593).

8400391 is a wasteful number, since it uses less digits than its factorization.

8400391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46592.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 8400391 is about 2898.3428023614. The cubic root of 8400391 is about 203.2824253694.

The spelling of 8400391 in words is "eight million, four hundred thousand, three hundred ninety-one".