221256557 has 8 divisors (see below), whose sum is σ = 222716472. Its totient is φ = 219801600.

The previous prime is 221256533. The next prime is 221256571. The reversal of 221256557 is 755652122.

221256557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 106894921 + 114361636 = 10339^2 + 10694^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221256557 - 2⁶ = 221256493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221216557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 129533 + ... + 131229.

It is an arithmetic number, because the mean of its divisors is an integer number (27839559).

Almost surely, 2^221256557 is an apocalyptic number.

It is an amenable number.

221256557 is a deficient number, since it is larger than the sum of its proper divisors (1459915).

221256557 is a wasteful number, since it uses less digits than its factorization.

221256557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2479.

The product of its digits is 42000, while the sum is 35.

The square root of 221256557 is about 14874.6951901543. The cubic root of 221256557 is about 604.8282252584.

It can be divided in two parts, 22125 and 6557, that added together give a palindrome (28682).

The spelling of 221256557 in words is "two hundred twenty-one million, two hundred fifty-six thousand, five hundred fifty-seven".