21004011 has 12 divisors (see below), whose sum is σ = 34673392. Its totient is φ = 12002256.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21004011 is 11040012.

It is a happy number.

It is not a de Polignac number, because 21004011 - 2⁷ = 21003883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21003984 and 21004002.

It is not an unprimeable number, because it can be changed into a prime (21004211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166636 + ... + 166761.

Almost surely, 2^21004011 is an apocalyptic number.

21004011 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21004011 is a deficient number, since it is larger than the sum of its proper divisors (13669381).

21004011 is a wasteful number, since it uses less digits than its factorization.

21004011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333410 (or 333407 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21004011 is about 4583.0133100396. The cubic root of 21004011 is about 275.9099816705.

Adding to 21004011 its reverse (11040012), we get a palindrome (32044023).

The spelling of 21004011 in words is "twenty-one million, four thousand, eleven".