20421806 has 8 divisors (see below), whose sum is σ = 30919320. Its totient is φ = 10115368.

The previous prime is 20421803. The next prime is 20421859. The reversal of 20421806 is 60812402.

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 (20421803) 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, 47501 + ... + 47928.

It is an arithmetic number, because the mean of its divisors is an integer number (3864915).

Almost surely, 2^20421806 is an apocalyptic number.

20421806 is a deficient number, since it is larger than the sum of its proper divisors (10497514).

20421806 is a wasteful number, since it uses less digits than its factorization.

20421806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95538.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 20421806 is about 4519.0492362885. The cubic root of 20421806 is about 273.3367641185.

The spelling of 20421806 in words is "twenty million, four hundred twenty-one thousand, eight hundred six".