20811641 has 8 divisors (see below), whose sum is σ = 21543144. Its totient is φ = 20090880.

The previous prime is 20811611. The next prime is 20811653. The reversal of 20811641 is 14611802.

It can be written as a sum of positive squares in 4 ways, for example, as 2876416 + 17935225 = 1696^2 + 4235^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20811641 is a prime.

It is a super-2 number, since 2×20811641² = 866248802225762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20811611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1361 + ... + 6593.

It is an arithmetic number, because the mean of its divisors is an integer number (2692893).

Almost surely, 2^20811641 is an apocalyptic number.

It is an amenable number.

20811641 is a deficient number, since it is larger than the sum of its proper divisors (731503).

20811641 is an equidigital number, since it uses as much as digits as its factorization.

20811641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5371.

The product of its (nonzero) digits is 384, while the sum is 23.

The square root of 20811641 is about 4561.9777509322. The cubic root of 20811641 is about 275.0650689001.

The spelling of 20811641 in words is "twenty million, eight hundred eleven thousand, six hundred forty-one".