161709805 has 8 divisors (see below), whose sum is σ = 194261112. Its totient is φ = 129228288.

The previous prime is 161709773. The next prime is 161709833. The reversal of 161709805 is 508907161.

It can be written as a sum of positive squares in 4 ways, for example, as 55145476 + 106564329 = 7426^2 + 10323^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 161709805 - 2⁵ = 161709773 is a prime.

It is a super-2 number, since 2×161709805² = 52300122066276050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12204 + ... + 21733.

It is an arithmetic number, because the mean of its divisors is an integer number (24282639).

Almost surely, 2^161709805 is an apocalyptic number.

It is an amenable number.

161709805 is a deficient number, since it is larger than the sum of its proper divisors (32551307).

161709805 is an equidigital number, since it uses as much as digits as its factorization.

161709805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34895.

The product of its (nonzero) digits is 15120, while the sum is 37.

The square root of 161709805 is about 12716.5170152837. The cubic root of 161709805 is about 544.8104775464.

The spelling of 161709805 in words is "one hundred sixty-one million, seven hundred nine thousand, eight hundred five".