161391616 has 33 divisors (see below), whose sum is σ = 323440329. Its totient is φ = 80492544.

The previous prime is 161391589. The next prime is 161391619. The reversal of 161391616 is 616193161.

The square root of 161391616 is 12704.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 108160000 + 53231616 = 10400^2 + 7296^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161391619) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 406330 + ... + 406726.

Almost surely, 2^161391616 is an apocalyptic number.

161391616 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

161391616 is the 12704-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161391616

161391616 is an abundant number, since it is smaller than the sum of its proper divisors (162048713).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

161391616 is an frugal number, since it uses more digits than its factorization.

161391616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 814 (or 399 counting only the distinct ones).

The product of its digits is 5832, while the sum is 34.

The cubic root of 161391616 is about 544.4529100200.

The spelling of 161391616 in words is "one hundred sixty-one million, three hundred ninety-one thousand, six hundred sixteen".