161285805 has 12 divisors (see below), whose sum is σ = 279562140. Its totient is φ = 86019072.

The previous prime is 161285797. The next prime is 161285833. The reversal of 161285805 is 508582161.

161285805 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 112593321 + 48692484 = 10611^2 + 6978^2 .

It is not a de Polignac number, because 161285805 - 2³ = 161285797 is a prime.

It is a super-2 number, since 2×161285805² = 52026221788996050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161285805.

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, 1792020 + ... + 1792109.

It is an arithmetic number, because the mean of its divisors is an integer number (23296845).

Almost surely, 2^161285805 is an apocalyptic number.

161285805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

161285805 is a deficient number, since it is larger than the sum of its proper divisors (118276335).

161285805 is a wasteful number, since it uses less digits than its factorization.

161285805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3584140 (or 3584137 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 36.

The square root of 161285805 is about 12699.8348414458. The cubic root of 161285805 is about 544.3338999113. Note that the first 3 decimals are identical.

It can be divided in two parts, 16 and 1285805, that added together give a palindrome (1285821).

The spelling of 161285805 in words is "one hundred sixty-one million, two hundred eighty-five thousand, eight hundred five".