81385245 has 12 divisors (see below), whose sum is σ = 141067836. Its totient is φ = 43405440.

The previous prime is 81385193. The next prime is 81385253. The reversal of 81385245 is 54258318.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16695396 + 64689849 = 4086^2 + 8043^2 .

It is not a de Polignac number, because 81385245 - 2²² = 77190941 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 904236 + ... + 904325.

It is an arithmetic number, because the mean of its divisors is an integer number (11755653).

Almost surely, 2^81385245 is an apocalyptic number.

It is an amenable number.

81385245 is a deficient number, since it is larger than the sum of its proper divisors (59682591).

81385245 is a wasteful number, since it uses less digits than its factorization.

81385245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1808572 (or 1808569 counting only the distinct ones).

The product of its digits is 38400, while the sum is 36.

The square root of 81385245 is about 9021.3771121708. The cubic root of 81385245 is about 433.3597363925.

The spelling of 81385245 in words is "eighty-one million, three hundred eighty-five thousand, two hundred forty-five".