21221051 has 2 divisors, whose sum is σ = 21221052. Its totient is φ = 21221050.

The previous prime is 21221047. The next prime is 21221063. The reversal of 21221051 is 15012212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21221051 - 2² = 21221047 is a prime.

It is a Chen prime.

It is equal to p_1343021 and since 21221051 and 1343021 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21221021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610525 + 10610526.

It is an arithmetic number, because the mean of its divisors is an integer number (10610526).

Almost surely, 2^21221051 is an apocalyptic number.

21221051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221051 is an equidigital number, since it uses as much as digits as its factorization.

21221051 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21221051 is about 4606.6311986092. The cubic root of 21221051 is about 276.8570771944.

Adding to 21221051 its reverse (15012212), we get a palindrome (36233263).

The spelling of 21221051 in words is "twenty-one million, two hundred twenty-one thousand, fifty-one".