20391806 has 8 divisors (see below), whose sum is σ = 32387040. Its totient is φ = 9596128.

The previous prime is 20391781. The next prime is 20391817. The reversal of 20391806 is 60819302.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 299846 + ... + 299913.

It is an arithmetic number, because the mean of its divisors is an integer number (4048380).

Almost surely, 2^20391806 is an apocalyptic number.

20391806 is a deficient number, since it is larger than the sum of its proper divisors (11995234).

20391806 is a wasteful number, since it uses less digits than its factorization.

20391806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 599778.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 20391806 is about 4515.7287341026. The cubic root of 20391806 is about 273.2028529850.

The spelling of 20391806 in words is "twenty million, three hundred ninety-one thousand, eight hundred six".