21759705 has 32 divisors (see below), whose sum is σ = 42203520. Its totient is φ = 10549440.

The previous prime is 21759667. The next prime is 21759709. The reversal of 21759705 is 50795712.

21759705 = 283² + 284² + ... + 444².

It is not a de Polignac number, because 21759705 - 2¹¹ = 21757657 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21759705.

It is not an unprimeable number, because it can be changed into a prime (21759709) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 5842 + ... + 8811.

It is an arithmetic number, because the mean of its divisors is an integer number (1318860).

Almost surely, 2^21759705 is an apocalyptic number.

It is an amenable number.

21759705 is a deficient number, since it is larger than the sum of its proper divisors (20443815).

21759705 is a wasteful number, since it uses less digits than its factorization.

21759705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14678 (or 14672 counting only the distinct ones).

The product of its (nonzero) digits is 22050, while the sum is 36.

The square root of 21759705 is about 4664.7298957174. The cubic root of 21759705 is about 279.1800202518.

The spelling of 21759705 in words is "twenty-one million, seven hundred fifty-nine thousand, seven hundred five".