81635565 has 16 divisors (see below), whose sum is σ = 142491456. Its totient is φ = 39580800.

The previous prime is 81635531. The next prime is 81635599. The reversal of 81635565 is 56553618.

It is an interprime number because it is at equal distance from previous prime (81635531) and next prime (81635599).

It is not a de Polignac number, because 81635565 - 2¹⁸ = 81373421 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 247216 + ... + 247545.

It is an arithmetic number, because the mean of its divisors is an integer number (8905716).

Almost surely, 2^81635565 is an apocalyptic number.

It is an amenable number.

81635565 is a deficient number, since it is larger than the sum of its proper divisors (60855891).

81635565 is a wasteful number, since it uses less digits than its factorization.

81635565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 494780.

The product of its digits is 108000, while the sum is 39.

The square root of 81635565 is about 9035.2401738969. The cubic root of 81635565 is about 433.8035825364.

The spelling of 81635565 in words is "eighty-one million, six hundred thirty-five thousand, five hundred sixty-five".