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128764921 = 373480133
BaseRepresentation
bin1111010110011…
…00101111111001
322222021221021011
413223030233321
5230430434141
620435513521
73122324635
oct753145771
9288257234
10128764921
1166758a9a
12371588a1
13208a557c
141315bdc5
15b487881
hex7accbf9

128764921 has 4 divisors (see below), whose sum is σ = 132245092. Its totient is φ = 125284752.

The previous prime is 128764897. The next prime is 128764939. The reversal of 128764921 is 129467821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129467821 = 718495403.

It can be written as a sum of positive squares in 2 ways, for example, as 120209296 + 8555625 = 10964^2 + 2925^2 .

It is a cyclic number.

It is not a de Polignac number, because 128764921 - 221 = 126667769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128764981) 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, 1740030 + ... + 1740103.

It is an arithmetic number, because the mean of its divisors is an integer number (33061273).

Almost surely, 2128764921 is an apocalyptic number.

It is an amenable number.

128764921 is a deficient number, since it is larger than the sum of its proper divisors (3480171).

128764921 is an equidigital number, since it uses as much as digits as its factorization.

128764921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3480170.

The product of its digits is 48384, while the sum is 40.

The square root of 128764921 is about 11347.4631966797. The cubic root of 128764921 is about 504.9703227340.

The spelling of 128764921 in words is "one hundred twenty-eight million, seven hundred sixty-four thousand, nine hundred twenty-one".

Divisors: 1 37 3480133 128764921