221261557 has 4 divisors (see below), whose sum is σ = 241376256. Its totient is φ = 201146860.

The previous prime is 221261549. The next prime is 221261597. The reversal of 221261557 is 755162122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221261557 - 2³ = 221261549 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221261507) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10057333 + ... + 10057354.

It is an arithmetic number, because the mean of its divisors is an integer number (60344064).

Almost surely, 2^221261557 is an apocalyptic number.

It is an amenable number.

221261557 is a deficient number, since it is larger than the sum of its proper divisors (20114699).

221261557 is a wasteful number, since it uses less digits than its factorization.

221261557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20114698.

The product of its digits is 8400, while the sum is 31.

The square root of 221261557 is about 14874.8632598757. The cubic root of 221261557 is about 604.8327812339.

The spelling of 221261557 in words is "two hundred twenty-one million, two hundred sixty-one thousand, five hundred fifty-seven".