21004686 has 12 divisors (see below), whose sum is σ = 45510192. Its totient is φ = 7001556.

The previous prime is 21004663. The next prime is 21004691. The reversal of 21004686 is 68640012.

It is a super-3 number, since 3×21004686³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 583446 + ... + 583481.

It is an arithmetic number, because the mean of its divisors is an integer number (3792516).

Almost surely, 2^21004686 is an apocalyptic number.

21004686 is an abundant number, since it is smaller than the sum of its proper divisors (24505506).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21004686 is a wasteful number, since it uses less digits than its factorization.

21004686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1166935 (or 1166932 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 21004686 is about 4583.0869509535. The cubic root of 21004686 is about 275.9129372527.

Adding to 21004686 its reverse (68640012), we get a palindrome (89644698).

It can be divided in two parts, 2100 and 4686, that added together give a triangular number (6786 = T₁₁₆).

The spelling of 21004686 in words is "twenty-one million, four thousand, six hundred eighty-six".