21171641 has 4 divisors (see below), whose sum is σ = 21240912. Its totient is φ = 21102372.

The previous prime is 21171637. The next prime is 21171649. The reversal of 21171641 is 14617112.

It is a happy number.

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 21171641 - 2² = 21171637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21171649) 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, 34175 + ... + 34788.

It is an arithmetic number, because the mean of its divisors is an integer number (5310228).

Almost surely, 2^21171641 is an apocalyptic number.

It is an amenable number.

21171641 is a deficient number, since it is larger than the sum of its proper divisors (69271).

21171641 is an equidigital number, since it uses as much as digits as its factorization.

21171641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69270.

The product of its digits is 336, while the sum is 23.

The square root of 21171641 is about 4601.2651521076. The cubic root of 21171641 is about 276.6420369681.

Adding to 21171641 its reverse (14617112), we get a palindrome (35788753).

It can be divided in two parts, 21171 and 641, that added together give a palindrome (21812).

The spelling of 21171641 in words is "twenty-one million, one hundred seventy-one thousand, six hundred forty-one".