221561879257 has 16 divisors (see below), whose sum is σ = 235366419600. Its totient is φ = 207843840000.

The previous prime is 221561879221. The next prime is 221561879269. The reversal of 221561879257 is 752978165122.

It can be written as a sum of positive squares in 8 ways, for example, as 12782337481 + 208779541776 = 113059^2 + 456924^2 .

It is a cyclic number.

It is not a de Polignac number, because 221561879257 - 2¹⁵ = 221561846489 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221561879198 and 221561879207.

It is not an unprimeable number, because it can be changed into a prime (221561279257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9835507 + ... + 9858007.

It is an arithmetic number, because the mean of its divisors is an integer number (14710401225).

Almost surely, 2^221561879257 is an apocalyptic number.

It is an amenable number.

221561879257 is a deficient number, since it is larger than the sum of its proper divisors (13804540343).

221561879257 is a wasteful number, since it uses less digits than its factorization.

221561879257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24396.

The product of its digits is 4233600, while the sum is 55.

The spelling of 221561879257 in words is "two hundred twenty-one billion, five hundred sixty-one million, eight hundred seventy-nine thousand, two hundred fifty-seven".