21720559255 has 16 divisors (see below), whose sum is σ = 26992183680. Its totient is φ = 16767844128.

The previous prime is 21720559247. The next prime is 21720559271. The reversal of 21720559255 is 55295502712.

It is a cyclic number.

It is not a de Polignac number, because 21720559255 - 2³ = 21720559247 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 590745 + ... + 626434.

It is an arithmetic number, because the mean of its divisors is an integer number (1687011480).

Almost surely, 2^21720559255 is an apocalyptic number.

21720559255 is a deficient number, since it is larger than the sum of its proper divisors (5271624425).

21720559255 is a wasteful number, since it uses less digits than its factorization.

21720559255 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1217310.

The product of its (nonzero) digits is 315000, while the sum is 43.

The spelling of 21720559255 in words is "twenty-one billion, seven hundred twenty million, five hundred fifty-nine thousand, two hundred fifty-five".