21621041 has 4 divisors (see below), whose sum is σ = 23284212. Its totient is φ = 19957872.

The previous prime is 21621029. The next prime is 21621053. The reversal of 21621041 is 14012612.

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

It is an interprime number because it is at equal distance from previous prime (21621029) and next prime (21621053).

It can be written as a sum of positive squares in 2 ways, for example, as 5740816 + 15880225 = 2396^2 + 3985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21621041 - 2¹⁰ = 21620017 is a prime.

It is a super-3 number, since 3×21621041³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21621001) 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, 831566 + ... + 831591.

It is an arithmetic number, because the mean of its divisors is an integer number (5821053).

Almost surely, 2^21621041 is an apocalyptic number.

It is an amenable number.

21621041 is a deficient number, since it is larger than the sum of its proper divisors (1663171).

21621041 is a wasteful number, since it uses less digits than its factorization.

21621041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1663170.

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21621041 is about 4649.8431156330. The cubic root of 21621041 is about 278.5857299943.

Adding to 21621041 its reverse (14012612), we get a palindrome (35633653).

The spelling of 21621041 in words is "twenty-one million, six hundred twenty-one thousand, forty-one".