83509781 has 2 divisors, whose sum is σ = 83509782. Its totient is φ = 83509780.

The previous prime is 83509687. The next prime is 83509799. The reversal of 83509781 is 18790538.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 83356900 + 152881 = 9130^2 + 391^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-83509781 is a prime.

It is a super-2 number, since 2×83509781² = 13947767045335922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (83509081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41754890 + 41754891.

It is an arithmetic number, because the mean of its divisors is an integer number (41754891).

Almost surely, 2^83509781 is an apocalyptic number.

It is an amenable number.

83509781 is a deficient number, since it is larger than the sum of its proper divisors (1).

83509781 is an equidigital number, since it uses as much as digits as its factorization.

83509781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 41.

The square root of 83509781 is about 9138.3686180850. The cubic root of 83509781 is about 437.0982975101.

The spelling of 83509781 in words is "eighty-three million, five hundred nine thousand, seven hundred eighty-one".