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81978059 = 166749177
BaseRepresentation
bin1001110001011…
…10001011001011
312201020220202102
410320232023023
5131441244214
612045024015
72013542042
oct470561313
9181226672
1081978059
1142302369
122355500b
1313ca3837
14ac5d559
1572e4bde
hex4e2e2cb

81978059 has 4 divisors (see below), whose sum is σ = 82028904. Its totient is φ = 81927216.

The previous prime is 81978053. The next prime is 81978067. The reversal of 81978059 is 95087918.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-81978059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81978053) 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, 22922 + ... + 26255.

It is an arithmetic number, because the mean of its divisors is an integer number (20507226).

Almost surely, 281978059 is an apocalyptic number.

81978059 is a deficient number, since it is larger than the sum of its proper divisors (50845).

81978059 is a wasteful number, since it uses less digits than its factorization.

81978059 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50844.

The product of its (nonzero) digits is 181440, while the sum is 47.

The square root of 81978059 is about 9054.1735680293. The cubic root of 81978059 is about 434.4093962307.

The spelling of 81978059 in words is "eighty-one million, nine hundred seventy-eight thousand, fifty-nine".

Divisors: 1 1667 49177 81978059