21405004 has 24 divisors (see below), whose sum is σ = 39408768. Its totient is φ = 10158720.

The previous prime is 21404983. The next prime is 21405047. The reversal of 21405004 is 40050412.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4944 + ... + 8200.

It is an arithmetic number, because the mean of its divisors is an integer number (1642032).

Almost surely, 2^21405004 is an apocalyptic number.

It is an amenable number.

21405004 is a deficient number, since it is larger than the sum of its proper divisors (18003764).

21405004 is a wasteful number, since it uses less digits than its factorization.

21405004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3345 (or 3343 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21405004 is about 4626.5542253388. The cubic root of 21405004 is about 277.6547479824.

Adding to 21405004 its reverse (40050412), we get a palindrome (61455416).

The spelling of 21405004 in words is "twenty-one million, four hundred five thousand, four".