Search a number
-
+
20815309 = 136715227
BaseRepresentation
bin100111101100…
…1110111001101
31110011112020101
41033121313031
520312042214
62022051101
7341633014
oct117316715
943145211
1020815309
1110827939
126b79a91
13440a568
142a9ba7b
151c62774
hex13d9dcd

20815309 has 4 divisors (see below), whose sum is σ = 20831904. Its totient is φ = 20798716.

The previous prime is 20815303. The next prime is 20815337. The reversal of 20815309 is 90351802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-20815309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20815303) 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, 6247 + ... + 8980.

It is an arithmetic number, because the mean of its divisors is an integer number (5207976).

Almost surely, 220815309 is an apocalyptic number.

It is an amenable number.

20815309 is a deficient number, since it is larger than the sum of its proper divisors (16595).

20815309 is a wasteful number, since it uses less digits than its factorization.

20815309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16594.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 20815309 is about 4562.3797518400. The cubic root of 20815309 is about 275.0812277957.

The spelling of 20815309 in words is "twenty million, eight hundred fifteen thousand, three hundred nine".

Divisors: 1 1367 15227 20815309