21401161 has 4 divisors (see below), whose sum is σ = 21484692. Its totient is φ = 21317632.

The previous prime is 21401137. The next prime is 21401203. The reversal of 21401161 is 16110412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17480761 + 3920400 = 4181^2 + 1980^2 .

It is a cyclic number.

It is not a de Polignac number, because 21401161 - 2¹⁷ = 21270089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21401111) 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 3 ways as a sum of consecutive naturals, for example, 41380 + ... + 41893.

It is an arithmetic number, because the mean of its divisors is an integer number (5371173).

Almost surely, 2^21401161 is an apocalyptic number.

It is an amenable number.

21401161 is a deficient number, since it is larger than the sum of its proper divisors (83531).

21401161 is an equidigital number, since it uses as much as digits as its factorization.

21401161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83530.

The product of its (nonzero) digits is 48, while the sum is 16.

The square root of 21401161 is about 4626.1388868040. The cubic root of 21401161 is about 277.6381305121.

Adding to 21401161 its reverse (16110412), we get a palindrome (37511573).

The spelling of 21401161 in words is "twenty-one million, four hundred one thousand, one hundred sixty-one".