Search a number
-
+
81252106805 = 5101281572581
BaseRepresentation
bin100101110101100000…
…0001100001000110101
321202201121011200122002
41023223000030020311
52312401014404210
6101154322345045
75604334340522
oct1135300141065
9252647150562
1081252106805
11315057724a1
12138b71bb185
13787b67160c
143d0b190149
1521a839d4a5
hex12eb00c235

81252106805 has 16 divisors (see below), whose sum is σ = 98818491888. Its totient is φ = 64128960000.

The previous prime is 81252106783. The next prime is 81252106813. The reversal of 81252106805 is 50860125218.

It can be written as a sum of positive squares in 8 ways, for example, as 99480676 + 81152626129 = 9974^2 + 284873^2 .

It is not a de Polignac number, because 81252106805 - 212 = 81252102709 is a prime.

It is a super-2 number, since 2×812521068052 (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 144386 + ... + 428195.

It is an arithmetic number, because the mean of its divisors is an integer number (6176155743).

Almost surely, 281252106805 is an apocalyptic number.

It is an amenable number.

81252106805 is a deficient number, since it is larger than the sum of its proper divisors (17566385083).

81252106805 is a wasteful number, since it uses less digits than its factorization.

81252106805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 572968.

The product of its (nonzero) digits is 38400, while the sum is 38.

The spelling of 81252106805 in words is "eighty-one billion, two hundred fifty-two million, one hundred six thousand, eight hundred five".

Divisors: 1 5 101 281 505 1405 28381 141905 572581 2862905 57830681 160895261 289153405 804476305 16250421361 81252106805