20813870 has 32 divisors (see below), whose sum is σ = 46711296. Its totient is φ = 6487200.

The previous prime is 20813839. The next prime is 20813879. The reversal of 20813870 is 7831802.

20813870 = 2633² + 2634² + 2635².

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20813879) 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 in 15 ways as a sum of consecutive naturals, for example, 12746 + ... + 14285.

It is an arithmetic number, because the mean of its divisors is an integer number (1459728).

Almost surely, 2^20813870 is an apocalyptic number.

20813870 is an abundant number, since it is smaller than the sum of its proper divisors (25897426).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20813870 is a wasteful number, since it uses less digits than its factorization.

20813870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27056.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 20813870 is about 4562.2220463279. Note that the first 3 decimals coincide. The cubic root of 20813870 is about 275.0748886952.

The spelling of 20813870 in words is "twenty million, eight hundred thirteen thousand, eight hundred seventy".