20400806 has 4 divisors (see below), whose sum is σ = 30601212. Its totient is φ = 10200402.

The previous prime is 20400803. The next prime is 20400811. The reversal of 20400806 is 60800402.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20400803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5100200 + ... + 5100203.

It is an arithmetic number, because the mean of its divisors is an integer number (7650303).

Almost surely, 2^20400806 is an apocalyptic number.

20400806 is a deficient number, since it is larger than the sum of its proper divisors (10200406).

20400806 is a wasteful number, since it uses less digits than its factorization.

20400806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10200405.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 20400806 is about 4516.7251410729. The cubic root of 20400806 is about 273.2430401076.

The spelling of 20400806 in words is "twenty million, four hundred thousand, eight hundred six".