21000161 has 8 divisors (see below), whose sum is σ = 25846464. Its totient is φ = 16615440.

The previous prime is 21000157. The next prime is 21000169. The reversal of 21000161 is 16100012.

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 21000161 - 2² = 21000157 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21000169) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 115295 + ... + 115476.

It is an arithmetic number, because the mean of its divisors is an integer number (3230808).

Almost surely, 2^21000161 is an apocalyptic number.

It is an amenable number.

21000161 is a deficient number, since it is larger than the sum of its proper divisors (4846303).

21000161 is a wasteful number, since it uses less digits than its factorization.

21000161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230791.

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

The square root of 21000161 is about 4582.5932614623. The cubic root of 21000161 is about 275.8931226947.

Adding to 21000161 its reverse (16100012), we get a palindrome (37100173).

The spelling of 21000161 in words is "twenty-one million, one hundred sixty-one", and thus it is an aban number.