21004143 has 16 divisors (see below), whose sum is σ = 29325312. Its totient is φ = 13356000.

The previous prime is 21004117. The next prime is 21004153. The reversal of 21004143 is 34140012.

It is not a de Polignac number, because 21004143 - 2⁸ = 21003887 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004153) 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, 5013 + ... + 8193.

It is an arithmetic number, because the mean of its divisors is an integer number (1832832).

Almost surely, 2^21004143 is an apocalyptic number.

21004143 is a deficient number, since it is larger than the sum of its proper divisors (8321169).

21004143 is a wasteful number, since it uses less digits than its factorization.

21004143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3286.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21004143 is about 4583.0277110225. The cubic root of 21004143 is about 275.9105596560.

Adding to 21004143 its reverse (34140012), we get a palindrome (55144155).

The spelling of 21004143 in words is "twenty-one million, four thousand, one hundred forty-three".