21512161 has 8 divisors (see below), whose sum is σ = 24703200. Its totient is φ = 18527040.

The previous prime is 21512147. The next prime is 21512213. The reversal of 21512161 is 16121512.

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 21512161 - 2⁵ = 21512129 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21512861) 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 7 ways as a sum of consecutive naturals, for example, 51256 + ... + 51673.

It is an arithmetic number, because the mean of its divisors is an integer number (3087900).

Almost surely, 2^21512161 is an apocalyptic number.

It is an amenable number.

21512161 is a deficient number, since it is larger than the sum of its proper divisors (3191039).

21512161 is a wasteful number, since it uses less digits than its factorization.

21512161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102959.

The product of its digits is 120, while the sum is 19.

The square root of 21512161 is about 4638.1204167205. The cubic root of 21512161 is about 278.1173055314.

Adding to 21512161 its reverse (16121512), we get a palindrome (37633673).

The spelling of 21512161 in words is "twenty-one million, five hundred twelve thousand, one hundred sixty-one".