21039404 has 12 divisors (see below), whose sum is σ = 38984904. Its totient is φ = 9900864.

The previous prime is 21039401. The next prime is 21039439. The reversal of 21039404 is 40493012.

It is a self number, because there is not a number n which added to its sum of digits gives 21039404.

It is not an unprimeable number, because it can be changed into a prime (21039401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 154634 + ... + 154769.

It is an arithmetic number, because the mean of its divisors is an integer number (3248742).

Almost surely, 2^21039404 is an apocalyptic number.

It is an amenable number.

21039404 is a deficient number, since it is larger than the sum of its proper divisors (17945500).

21039404 is a wasteful number, since it uses less digits than its factorization.

21039404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309424 (or 309422 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21039404 is about 4586.8730089245. The cubic root of 21039404 is about 276.0648695803.

The spelling of 21039404 in words is "twenty-one million, thirty-nine thousand, four hundred four".