81775505 has 16 divisors (see below), whose sum is σ = 116017920. Its totient is φ = 54140352.

The previous prime is 81775493. The next prime is 81775517. The reversal of 81775505 is 50557718.

It is an interprime number because it is at equal distance from previous prime (81775493) and next prime (81775517).

It is not a de Polignac number, because 81775505 - 2²² = 77581201 is a prime.

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, 39269 + ... + 41298.

It is an arithmetic number, because the mean of its divisors is an integer number (7251120).

Almost surely, 2^81775505 is an apocalyptic number.

It is an amenable number.

81775505 is a deficient number, since it is larger than the sum of its proper divisors (34242415).

81775505 is a wasteful number, since it uses less digits than its factorization.

81775505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80608.

The product of its (nonzero) digits is 49000, while the sum is 38.

The square root of 81775505 is about 9042.9809797434. The cubic root of 81775505 is about 434.0513169586.

The spelling of 81775505 in words is "eighty-one million, seven hundred seventy-five thousand, five hundred five".