161000021 has 32 divisors (see below), whose sum is σ = 203374080. Its totient is φ = 124084224.

The previous prime is 161000017. The next prime is 161000057. The reversal of 161000021 is 120000161.

It is a cyclic number.

It is not a de Polignac number, because 161000021 - 2² = 161000017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 160999966 and 161000011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161000921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 834101 + ... + 834293.

It is an arithmetic number, because the mean of its divisors is an integer number (6355440).

Almost surely, 2^161000021 is an apocalyptic number.

It is an amenable number.

161000021 is a deficient number, since it is larger than the sum of its proper divisors (42374059).

161000021 is a wasteful number, since it uses less digits than its factorization.

161000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 161000021 is about 12688.5783679654. The cubic root of 161000021 is about 544.0122061942.

Adding to 161000021 its reverse (120000161), we get a palindrome (281000182).

The spelling of 161000021 in words is "one hundred sixty-one million, twenty-one", and thus it is an aban number.