21152161 has 4 divisors (see below), whose sum is σ = 21196800. Its totient is φ = 21107524.

The previous prime is 21152143. The next prime is 21152207. The reversal of 21152161 is 16125112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21152161 - 2¹¹ = 21150113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21152561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21601 + ... + 22558.

It is an arithmetic number, because the mean of its divisors is an integer number (5299200).

Almost surely, 2^21152161 is an apocalyptic number.

It is an amenable number.

21152161 is a deficient number, since it is larger than the sum of its proper divisors (44639).

21152161 is an equidigital number, since it uses as much as digits as its factorization.

21152161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44638.

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

The square root of 21152161 is about 4599.1478558533. The cubic root of 21152161 is about 276.5571649369.

Adding to 21152161 its reverse (16125112), we get a palindrome (37277273).

The spelling of 21152161 in words is "twenty-one million, one hundred fifty-two thousand, one hundred sixty-one".