21022913 has 2 divisors, whose sum is σ = 21022914. Its totient is φ = 21022912.

The previous prime is 21022909. The next prime is 21022921. The reversal of 21022913 is 31922012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20948929 + 73984 = 4577^2 + 272^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022913 - 2² = 21022909 is a prime.

It is not a weakly prime, because it can be changed into another prime (21022213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511456 + 10511457.

It is an arithmetic number, because the mean of its divisors is an integer number (10511457).

Almost surely, 2^21022913 is an apocalyptic number.

It is an amenable number.

21022913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022913 is an equidigital number, since it uses as much as digits as its factorization.

21022913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 21022913 is about 4585.0750266490. The cubic root of 21022913 is about 275.9927228005.

Adding to 21022913 its reverse (31922012), we get a palindrome (52944925).

The spelling of 21022913 in words is "twenty-one million, twenty-two thousand, nine hundred thirteen".