21112057 has 4 divisors (see below), whose sum is σ = 21172900. Its totient is φ = 21051216.

The previous prime is 21112043. The next prime is 21112061. The reversal of 21112057 is 75021112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17505856 + 3606201 = 4184^2 + 1899^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112057 - 2¹⁹ = 20587769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29898 + ... + 30595.

It is an arithmetic number, because the mean of its divisors is an integer number (5293225).

Almost surely, 2^21112057 is an apocalyptic number.

It is an amenable number.

21112057 is a deficient number, since it is larger than the sum of its proper divisors (60843).

21112057 is an equidigital number, since it uses as much as digits as its factorization.

21112057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60842.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 21112057 is about 4594.7858491991. The cubic root of 21112057 is about 276.3822723985.

Adding to 21112057 its reverse (75021112), we get a palindrome (96133169).

The spelling of 21112057 in words is "twenty-one million, one hundred twelve thousand, fifty-seven".