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1230806781 = 32136756309
BaseRepresentation
bin100100101011100…
…1001111011111101
310011202222110111100
41021113021323331
510010041304111
6322044243313
742333453651
oct11127117375
93152873440
101230806781
11581838396
122a4240539
13167cbc749
14b966ca61
15730c3756
hex495c9efd

1230806781 has 6 divisors (see below), whose sum is σ = 1777832030. Its totient is φ = 820537848.

The previous prime is 1230806779. The next prime is 1230806803. The reversal of 1230806781 is 1876080321.

It can be written as a sum of positive squares in only one way, i.e., 736633881 + 494172900 = 27141^2 + 22230^2 .

It is not a de Polignac number, because 1230806781 - 21 = 1230806779 is a prime.

It is a super-2 number, since 2×12308067812 = 3029770664311163922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1230806711) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 68378146 + ... + 68378163.

Almost surely, 21230806781 is an apocalyptic number.

It is an amenable number.

1230806781 is a deficient number, since it is larger than the sum of its proper divisors (547025249).

1230806781 is a wasteful number, since it uses less digits than its factorization.

1230806781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136756315 (or 136756312 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 1230806781 is about 35082.8559413284. The cubic root of 1230806781 is about 1071.6754782359.

The spelling of 1230806781 in words is "one billion, two hundred thirty million, eight hundred six thousand, seven hundred eighty-one".

Divisors: 1 3 9 136756309 410268927 1230806781