21063765 has 48 divisors (see below), whose sum is σ = 36957888. Its totient is φ = 10235904.

The previous prime is 21063751. The next prime is 21063769. The reversal of 21063765 is 56736012.

It is not a de Polignac number, because 21063765 - 2⁵ = 21063733 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21063769) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 186349 + ... + 186461.

It is an arithmetic number, because the mean of its divisors is an integer number (769956).

Almost surely, 2^21063765 is an apocalyptic number.

It is an amenable number.

21063765 is a deficient number, since it is larger than the sum of its proper divisors (15894123).

21063765 is a wasteful number, since it uses less digits than its factorization.

21063765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 181 counting only the distinct ones).

The product of its (nonzero) digits is 7560, while the sum is 30.

The square root of 21063765 is about 4589.5277534840. The cubic root of 21063765 is about 276.1713780204.

Adding to 21063765 its reverse (56736012), we get a palindrome (77799777).

The spelling of 21063765 in words is "twenty-one million, sixty-three thousand, seven hundred sixty-five".