21065265 has 40 divisors (see below), whose sum is σ = 40676328. Its totient is φ = 10368000.

The previous prime is 21065207. The next prime is 21065273. The reversal of 21065265 is 56256012.

21065265 is a `hidden beast` number, since 2 + 1 + 0 + 652 + 6 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 571536 + 20493729 = 756^2 + 4527^2 .

It is not a de Polignac number, because 21065265 - 2⁶ = 21065201 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3265 + ... + 7265.

Almost surely, 2^21065265 is an apocalyptic number.

It is an amenable number.

21065265 is a deficient number, since it is larger than the sum of its proper divisors (19611063).

21065265 is a wasteful number, since it uses less digits than its factorization.

21065265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4031 (or 4022 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 21065265 is about 4589.6911660808. The cubic root of 21065265 is about 276.1779334682.

The spelling of 21065265 in words is "twenty-one million, sixty-five thousand, two hundred sixty-five".