72090805 has 4 divisors (see below), whose sum is σ = 86508972. Its totient is φ = 57672640.

The previous prime is 72090797. The next prime is 72090827. The reversal of 72090805 is 50809027.

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 38427601 + 33663204 = 6199^2 + 5802^2 .

It is not a de Polignac number, because 72090805 - 2³ = 72090797 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 3 ways as a sum of consecutive naturals, for example, 7209076 + ... + 7209085.

It is an arithmetic number, because the mean of its divisors is an integer number (21627243).

Almost surely, 2^72090805 is an apocalyptic number.

It is an amenable number.

72090805 is a deficient number, since it is larger than the sum of its proper divisors (14418167).

72090805 is a wasteful number, since it uses less digits than its factorization.

72090805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14418166.

The product of its (nonzero) digits is 5040, while the sum is 31.

The square root of 72090805 is about 8490.6304241793. The cubic root of 72090805 is about 416.1915818904.

The spelling of 72090805 in words is "seventy-two million, ninety thousand, eight hundred five".