221747751801 has 9 divisors (see below), whose sum is σ = 320304348741. Its totient is φ = 147830892732.

The previous prime is 221747751787. The next prime is 221747751803. The reversal of 221747751801 is 108157747122.

It is a happy number.

The square root of 221747751801 is 470901.

It is a perfect power (a square), and thus also a powerful number.

221747751801 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 221747751801 - 2²¹ = 221745654649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (221747751803) by changing a digit.

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 8 ways as a sum of consecutive naturals, for example, 1334220 + ... + 1491186.

Almost surely, 2^221747751801 is an apocalyptic number.

221747751801 is the 470901-st square number.

221747751801 is the 235451-st centered octagonal number.

It is an amenable number.

221747751801 is a deficient number, since it is larger than the sum of its proper divisors (98556596940).

221747751801 is an frugal number, since it uses more digits than its factorization.

221747751801 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 313940 (or 156970 counting only the distinct ones).

The product of its (nonzero) digits is 219520, while the sum is 45.

The spelling of 221747751801 in words is "two hundred twenty-one billion, seven hundred forty-seven million, seven hundred fifty-one thousand, eight hundred one".