75720809 has 4 divisors (see below), whose sum is σ = 77567700. Its totient is φ = 73873920.

The previous prime is 75720803. The next prime is 75720847. The reversal of 75720809 is 90802757.

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

It can be written as a sum of positive squares in 2 ways, for example, as 7823209 + 67897600 = 2797^2 + 8240^2 .

It is a cyclic number.

It is not a de Polignac number, because 75720809 - 2⁴ = 75720793 is a prime.

It is a super-2 number, since 2×75720809² = 11467281831228962, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (75720803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 923384 + ... + 923465.

It is an arithmetic number, because the mean of its divisors is an integer number (19391925).

Almost surely, 2^75720809 is an apocalyptic number.

It is an amenable number.

75720809 is a deficient number, since it is larger than the sum of its proper divisors (1846891).

75720809 is a wasteful number, since it uses less digits than its factorization.

75720809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1846890.

The product of its (nonzero) digits is 35280, while the sum is 38.

The square root of 75720809 is about 8701.7704520402. The cubic root of 75720809 is about 423.0630360968.

The spelling of 75720809 in words is "seventy-five million, seven hundred twenty thousand, eight hundred nine".