21122005 has 32 divisors (see below), whose sum is σ = 28016640. Its totient is φ = 15240960.

The previous prime is 21121999. The next prime is 21122009. The reversal of 21122005 is 50022112.

It is not a de Polignac number, because 21122005 - 2⁹ = 21121493 is a prime.

It is a super-2 number, since 2×21122005² = 892278190440050, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122009) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 166252 + ... + 166378.

It is an arithmetic number, because the mean of its divisors is an integer number (875520).

Almost surely, 2^21122005 is an apocalyptic number.

It is an amenable number.

21122005 is a deficient number, since it is larger than the sum of its proper divisors (6894635).

21122005 is a wasteful number, since it uses less digits than its factorization.

21122005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21122005 is about 4595.8682531161. The cubic root of 21122005 is about 276.4256760187.

Adding to 21122005 its reverse (50022112), we get a palindrome (71144117).

The spelling of 21122005 in words is "twenty-one million, one hundred twenty-two thousand, five".