21200557 has 4 divisors (see below), whose sum is σ = 24229216. Its totient is φ = 18171900.

The previous prime is 21200539. The next prime is 21200563. The reversal of 21200557 is 75500212.

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 21200557 - 2¹⁵ = 21167789 is a prime.

It is a super-2 number, since 2×21200557² = 898927234220498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200507) 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, 1514319 + ... + 1514332.

It is an arithmetic number, because the mean of its divisors is an integer number (6057304).

Almost surely, 2^21200557 is an apocalyptic number.

It is an amenable number.

21200557 is a deficient number, since it is larger than the sum of its proper divisors (3028659).

21200557 is an equidigital number, since it uses as much as digits as its factorization.

21200557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3028658.

The product of its (nonzero) digits is 700, while the sum is 22.

The square root of 21200557 is about 4604.4062592260. The cubic root of 21200557 is about 276.7679245816.

Adding to 21200557 its reverse (75500212), we get a palindrome (96700769).

The spelling of 21200557 in words is "twenty-one million, two hundred thousand, five hundred fifty-seven".