90720517 has 4 divisors (see below), whose sum is σ = 96057036. Its totient is φ = 85384000.

The previous prime is 90720503. The next prime is 90720521. The reversal of 90720517 is 71502709.

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 34680321 + 56040196 = 5889^2 + 7486^2 .

It is a cyclic number.

It is not a de Polignac number, because 90720517 - 2⁷ = 90720389 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 not an unprimeable number, because it can be changed into a prime (90723517) 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, 2668234 + ... + 2668267.

It is an arithmetic number, because the mean of its divisors is an integer number (24014259).

Almost surely, 2^90720517 is an apocalyptic number.

It is an amenable number.

90720517 is a deficient number, since it is larger than the sum of its proper divisors (5336519).

90720517 is a wasteful number, since it uses less digits than its factorization.

90720517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5336518.

The product of its (nonzero) digits is 4410, while the sum is 31.

The square root of 90720517 is about 9524.7318597428. The cubic root of 90720517 is about 449.3331967912. Note that the first 3 decimals are identical.

The spelling of 90720517 in words is "ninety million, seven hundred twenty thousand, five hundred seventeen".