21322621 has 2 divisors, whose sum is σ = 21322622. Its totient is φ = 21322620.

The previous prime is 21322601. The next prime is 21322661. The reversal of 21322621 is 12622312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11799225 + 9523396 = 3435^2 + 3086^2 .

It is a cyclic number.

It is not a de Polignac number, because 21322621 - 2⁷ = 21322493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21322601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661310 + 10661311.

It is an arithmetic number, because the mean of its divisors is an integer number (10661311).

Almost surely, 2^21322621 is an apocalyptic number.

It is an amenable number.

21322621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21322621 is an equidigital number, since it uses as much as digits as its factorization.

21322621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 19.

The square root of 21322621 is about 4617.6423638043. The cubic root of 21322621 is about 277.2980799861.

Adding to 21322621 its reverse (12622312), we get a palindrome (33944933).

It can be divided in two parts, 2132 and 2621, that added together give a triangular number (4753 = T₉₇).

The spelling of 21322621 in words is "twenty-one million, three hundred twenty-two thousand, six hundred twenty-one".