81787525 has 6 divisors (see below), whose sum is σ = 101416562. Its totient is φ = 65430000.

The previous prime is 81787507. The next prime is 81787549. The reversal of 81787525 is 52578718.

It can be written as a sum of positive squares in 3 ways, for example, as 5207524 + 76580001 = 2282^2 + 8751^2 .

It is not a de Polignac number, because 81787525 - 2¹⁷ = 81656453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1635726 + ... + 1635775.

Almost surely, 2^81787525 is an apocalyptic number.

It is an amenable number.

81787525 is a deficient number, since it is larger than the sum of its proper divisors (19629037).

81787525 is a wasteful number, since it uses less digits than its factorization.

81787525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3271511 (or 3271506 counting only the distinct ones).

The product of its digits is 156800, while the sum is 43.

The square root of 81787525 is about 9043.6455591758. The cubic root of 81787525 is about 434.0725826633.

The spelling of 81787525 in words is "eighty-one million, seven hundred eighty-seven thousand, five hundred twenty-five".