21710565 has 32 divisors (see below), whose sum is σ = 39143040. Its totient is φ = 11415168.

The previous prime is 21710537. The next prime is 21710567. The reversal of 21710565 is 56501712.

It is not a de Polignac number, because 21710565 - 2²⁰ = 20661989 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21710567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8754 + ... + 10956.

It is an arithmetic number, because the mean of its divisors is an integer number (1223220).

Almost surely, 2^21710565 is an apocalyptic number.

It is an amenable number.

21710565 is a deficient number, since it is larger than the sum of its proper divisors (17432475).

21710565 is a wasteful number, since it uses less digits than its factorization.

21710565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2290 (or 2284 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 21710565 is about 4659.4597326300. The cubic root of 21710565 is about 278.9697041910.

The spelling of 21710565 in words is "twenty-one million, seven hundred ten thousand, five hundred sixty-five".