21115641 has 16 divisors (see below), whose sum is σ = 29102528. Its totient is φ = 13608000.

The previous prime is 21115603. The next prime is 21115651. The reversal of 21115641 is 14651112.

It is not a de Polignac number, because 21115641 - 2¹¹ = 21113593 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21115651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19566 + ... + 20616.

It is an arithmetic number, because the mean of its divisors is an integer number (1818908).

Almost surely, 2^21115641 is an apocalyptic number.

It is an amenable number.

21115641 is a deficient number, since it is larger than the sum of its proper divisors (7986887).

21115641 is a wasteful number, since it uses less digits than its factorization.

21115641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1272.

The product of its digits is 240, while the sum is 21.

The square root of 21115641 is about 4595.1758399435. The cubic root of 21115641 is about 276.3979111402.

Adding to 21115641 its reverse (14651112), we get a palindrome (35766753).

The spelling of 21115641 in words is "twenty-one million, one hundred fifteen thousand, six hundred forty-one".