20391406 has 8 divisors (see below), whose sum is σ = 34956720. Its totient is φ = 8739168.

The previous prime is 20391377. The next prime is 20391407. The reversal of 20391406 is 60419302.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20391407) 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, 728251 + ... + 728278.

It is an arithmetic number, because the mean of its divisors is an integer number (4369590).

Almost surely, 2^20391406 is an apocalyptic number.

20391406 is a deficient number, since it is larger than the sum of its proper divisors (14565314).

20391406 is a wasteful number, since it uses less digits than its factorization.

20391406 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1456538.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 20391406 is about 4515.6844442454. The cubic root of 20391406 is about 273.2010666162.

The spelling of 20391406 in words is "twenty million, three hundred ninety-one thousand, four hundred six".