161721716 has 12 divisors (see below), whose sum is σ = 304783332. Its totient is φ = 74640768.

The previous prime is 161721701. The next prime is 161721737. The reversal of 161721716 is 617127161.

It can be written as a sum of positive squares in 2 ways, for example, as 41731600 + 119990116 = 6460^2 + 10954^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1554965 + ... + 1555068.

It is an arithmetic number, because the mean of its divisors is an integer number (25398611).

Almost surely, 2^161721716 is an apocalyptic number.

It is an amenable number.

161721716 is a deficient number, since it is larger than the sum of its proper divisors (143061616).

161721716 is a wasteful number, since it uses less digits than its factorization.

161721716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3110050 (or 3110048 counting only the distinct ones).

The product of its digits is 3528, while the sum is 32.

The square root of 161721716 is about 12716.9853345830. The cubic root of 161721716 is about 544.8238535200.

Adding to 161721716 its reverse (617127161), we get a palindrome (778848877).

The spelling of 161721716 in words is "one hundred sixty-one million, seven hundred twenty-one thousand, seven hundred sixteen".