16621720555 has 16 divisors (see below), whose sum is σ = 21767032800. Its totient is φ = 12084252160.

The previous prime is 16621720547. The next prime is 16621720561. The reversal of 16621720555 is 55502712661.

It is not a de Polignac number, because 16621720555 - 2³ = 16621720547 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 108051 + ... + 211939.

It is an arithmetic number, because the mean of its divisors is an integer number (1360439550).

Almost surely, 2^16621720555 is an apocalyptic number.

16621720555 is a deficient number, since it is larger than the sum of its proper divisors (5145312245).

16621720555 is a wasteful number, since it uses less digits than its factorization.

16621720555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106814.

The product of its (nonzero) digits is 126000, while the sum is 40.

The spelling of 16621720555 in words is "sixteen billion, six hundred twenty-one million, seven hundred twenty thousand, five hundred fifty-five".