21022901 has 2 divisors, whose sum is σ = 21022902. Its totient is φ = 21022900.

The previous prime is 21022889. The next prime is 21022909. The reversal of 21022901 is 10922012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21022225 + 676 = 4585^2 + 26^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022901 - 2²² = 16828597 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21022901.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21022909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10511450 + 10511451.

It is an arithmetic number, because the mean of its divisors is an integer number (10511451).

Almost surely, 2^21022901 is an apocalyptic number.

It is an amenable number.

21022901 is a deficient number, since it is larger than the sum of its proper divisors (1).

21022901 is an equidigital number, since it uses as much as digits as its factorization.

21022901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21022901 is about 4585.0737180551. The cubic root of 21022901 is about 275.9926702877.

Adding to 21022901 its reverse (10922012), we get a palindrome (31944913).

The spelling of 21022901 in words is "twenty-one million, twenty-two thousand, nine hundred one".