221729917765 has 4 divisors (see below), whose sum is σ = 266075901324. Its totient is φ = 177383934208.

The previous prime is 221729917751. The next prime is 221729917781. The reversal of 221729917765 is 567719927122.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 567719927122 = 2 ⋅283859963561.

It can be written as a sum of positive squares in 2 ways, for example, as 92815887649 + 128914030116 = 304657^2 + 359046^2 .

It is a cyclic number.

It is not a de Polignac number, because 221729917765 - 2³⁷ = 84290964293 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22172991772 + ... + 22172991781.

It is an arithmetic number, because the mean of its divisors is an integer number (66518975331).

Almost surely, 2^221729917765 is an apocalyptic number.

It is an amenable number.

221729917765 is a deficient number, since it is larger than the sum of its proper divisors (44345983559).

221729917765 is an equidigital number, since it uses as much as digits as its factorization.

221729917765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44345983558.

The product of its digits is 6667920, while the sum is 58.

The spelling of 221729917765 in words is "two hundred twenty-one billion, seven hundred twenty-nine million, nine hundred seventeen thousand, seven hundred sixty-five".