81605284 has 6 divisors (see below), whose sum is σ = 142809254. Its totient is φ = 40802640.

The previous prime is 81605267. The next prime is 81605291. The reversal of 81605284 is 48250618.

It can be written as a sum of positive squares in only one way, i.e., 81000000 + 605284 = 9000^2 + 778^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200657 + ... + 10200664.

Almost surely, 2^81605284 is an apocalyptic number.

It is an amenable number.

81605284 is a deficient number, since it is larger than the sum of its proper divisors (61203970).

81605284 is a wasteful number, since it uses less digits than its factorization.

81605284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20401325 (or 20401323 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The square root of 81605284 is about 9033.5643020903. The cubic root of 81605284 is about 433.7499391241.

It can be divided in two parts, 81 and 605284, that multiplied together give a square (49028004 = 7002²).

The spelling of 81605284 in words is "eighty-one million, six hundred five thousand, two hundred eighty-four".