21201724555 has 16 divisors (see below), whose sum is σ = 28209989088. Its totient is φ = 15166656000.

The previous prime is 21201724529. The next prime is 21201724589. The reversal of 21201724555 is 55542710212.

It is a de Polignac number, because none of the positive numbers 2^k-21201724555 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21201724555.

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, 3156366 + ... + 3163075.

It is an arithmetic number, because the mean of its divisors is an integer number (1763124318).

Almost surely, 2^21201724555 is an apocalyptic number.

21201724555 is a deficient number, since it is larger than the sum of its proper divisors (7008264533).

21201724555 is a wasteful number, since it uses less digits than its factorization.

21201724555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6319518.

The product of its (nonzero) digits is 28000, while the sum is 34.

The spelling of 21201724555 in words is "twenty-one billion, two hundred one million, seven hundred twenty-four thousand, five hundred fifty-five".