Search a number
-
+
28381531 = 61465271
BaseRepresentation
bin110110001000…
…1000101011011
31222101221010211
41230101011123
524231202111
62452151551
7463144663
oct154210533
958357124
1028381531
1115025512
1296085b7
135b59409
143aab1a3
152759521
hex1b1115b

28381531 has 4 divisors (see below), whose sum is σ = 28846864. Its totient is φ = 27916200.

The previous prime is 28381519. The next prime is 28381541. The reversal of 28381531 is 13518382.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13518382 = 26759191.

It is a cyclic number.

It is not a de Polignac number, because 28381531 - 27 = 28381403 is a prime.

It is a super-2 number, since 2×283815312 = 1611022603807922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28381493 and 28381502.

It is not an unprimeable number, because it can be changed into a prime (28381511) 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, 232575 + ... + 232696.

It is an arithmetic number, because the mean of its divisors is an integer number (7211716).

Almost surely, 228381531 is an apocalyptic number.

28381531 is the 2383-rd centered decagonal number.

28381531 is a deficient number, since it is larger than the sum of its proper divisors (465333).

28381531 is an equidigital number, since it uses as much as digits as its factorization.

28381531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 465332.

The product of its digits is 5760, while the sum is 31.

The square root of 28381531 is about 5327.4319329298. The cubic root of 28381531 is about 305.0319092298.

The spelling of 28381531 in words is "twenty-eight million, three hundred eighty-one thousand, five hundred thirty-one".

Divisors: 1 61 465271 28381531