21004965 has 12 divisors (see below), whose sum is σ = 36408684. Its totient is φ = 11202624.

The previous prime is 21004931. The next prime is 21004981. The reversal of 21004965 is 56940012.

It can be written as a sum of positive squares in 2 ways, for example, as 14130081 + 6874884 = 3759^2 + 2622^2 .

It is not a de Polignac number, because 21004965 - 2⁶ = 21004901 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 233344 + ... + 233433.

It is an arithmetic number, because the mean of its divisors is an integer number (3034057).

Almost surely, 2^21004965 is an apocalyptic number.

It is an amenable number.

21004965 is a deficient number, since it is larger than the sum of its proper divisors (15403719).

21004965 is a wasteful number, since it uses less digits than its factorization.

21004965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 466788 (or 466785 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21004965 is about 4583.1173888523. The cubic root of 21004965 is about 275.9141588748.

Adding to 21004965 its reverse (56940012), we get a palindrome (77944977).

The spelling of 21004965 in words is "twenty-one million, four thousand, nine hundred sixty-five".