161621217 has 16 divisors (see below), whose sum is σ = 245911680. Its totient is φ = 104834736.

The previous prime is 161621209. The next prime is 161621267. The reversal of 161621217 is 712126161.

It is a happy number.

161621217 is a `hidden beast` number, since 1 + 616 + 21 + 21 + 7 = 666.

It is not a de Polignac number, because 161621217 - 2³ = 161621209 is a prime.

It is a super-2 number, since 2×161621217² = 52242835569122178, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (161621267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 79893 + ... + 81890.

It is an arithmetic number, because the mean of its divisors is an integer number (15369480).

Almost surely, 2^161621217 is an apocalyptic number.

It is an amenable number.

161621217 is a deficient number, since it is larger than the sum of its proper divisors (84290463).

161621217 is a wasteful number, since it uses less digits than its factorization.

161621217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161829 (or 161823 counting only the distinct ones).

The product of its digits is 1008, while the sum is 27.

The square root of 161621217 is about 12713.0333516435. The cubic root of 161621217 is about 544.7109731975.

Adding to 161621217 its reverse (712126161), we get a palindrome (873747378).

The spelling of 161621217 in words is "one hundred sixty-one million, six hundred twenty-one thousand, two hundred seventeen".