81510885 has 12 divisors (see below), whose sum is σ = 141285612. Its totient is φ = 43472448.

The previous prime is 81510883. The next prime is 81510887. The reversal of 81510885 is 58801518.

It is an interprime number because it is at equal distance from previous prime (81510883) and next prime (81510887).

It can be written as a sum of positive squares in 2 ways, for example, as 47568609 + 33942276 = 6897^2 + 5826^2 .

It is not a de Polignac number, because 81510885 - 2¹ = 81510883 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81510881) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 905632 + ... + 905721.

It is an arithmetic number, because the mean of its divisors is an integer number (11773801).

Almost surely, 2^81510885 is an apocalyptic number.

It is an amenable number.

81510885 is a deficient number, since it is larger than the sum of its proper divisors (59774727).

81510885 is a wasteful number, since it uses less digits than its factorization.

81510885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1811364 (or 1811361 counting only the distinct ones).

The product of its (nonzero) digits is 12800, while the sum is 36.

The square root of 81510885 is about 9028.3378868981. The cubic root of 81510885 is about 433.5826241460.

The spelling of 81510885 in words is "eighty-one million, five hundred ten thousand, eight hundred eighty-five".