20181641 has 4 divisors (see below), whose sum is σ = 20256384. Its totient is φ = 20106900.

The previous prime is 20181631. The next prime is 20181643. The reversal of 20181641 is 14618102.

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, and also an emirpimes, since its reverse is a distinct semiprime: 14618102 = 2 ⋅7309051.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20181641 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20181643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36965 + ... + 37506.

It is an arithmetic number, because the mean of its divisors is an integer number (5064096).

Almost surely, 2^20181641 is an apocalyptic number.

It is an amenable number.

20181641 is a deficient number, since it is larger than the sum of its proper divisors (74743).

20181641 is an equidigital number, since it uses as much as digits as its factorization.

20181641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74742.

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

The square root of 20181641 is about 4492.3981346270. The cubic root of 20181641 is about 272.2610356307.

Adding to 20181641 its reverse (14618102), we get a palindrome (34799743).

The spelling of 20181641 in words is "twenty million, one hundred eighty-one thousand, six hundred forty-one".