21220057 has 4 divisors (see below), whose sum is σ = 21237376. Its totient is φ = 21202740.

The previous prime is 21220019. The next prime is 21220103. The reversal of 21220057 is 75002212.

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 21220057 - 2⁷ = 21219929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6669 + ... + 9322.

It is an arithmetic number, because the mean of its divisors is an integer number (5309344).

Almost surely, 2^21220057 is an apocalyptic number.

It is an amenable number.

21220057 is a deficient number, since it is larger than the sum of its proper divisors (17319).

21220057 is a wasteful number, since it uses less digits than its factorization.

21220057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17318.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 21220057 is about 4606.5233093951. The cubic root of 21220057 is about 276.8527544391.

Adding to 21220057 its reverse (75002212), we get a palindrome (96222269).

The spelling of 21220057 in words is "twenty-one million, two hundred twenty thousand, fifty-seven".